Comparison of programming languages is a common topic of discussion among software engineer

Software engineer

A software engineer is an engineer who applies the principles of software engineering to the design, development, testing, and evaluation of the software and systems that make computers or anything containing software, such as computer chips, work.- Overview :...

s. Basic instructions of several programming language

Programming language

A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....

s are compared here.

Conventions of this article

The bold is the literal code. The non-bold is interpreted by the reader. Statements in guillemets

Guillemets

Guillemets , also called angle quotes, are line segments, pointed as if arrows , sometimes forming a complementary set of punctuation marks used as a form of quotation mark....

 (« … ») are optional. indicates a necessary indent.

Integer

Integer (computer science)

In computer science, an integer is a datum of integral data type, a data type which represents some finite subset of the mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values....

s

	8 bit (byte Byte The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer... )		16 bit (short integer)		32 bit		64 bit (long integer)		Word size		Arbitrarily precise (bignum Arbitrary-precision arithmetic In computer science, arbitrary-precision arithmetic indicates that calculations are performed on numbers whose digits of precision are limited only by the available memory of the host system. This contrasts with the faster fixed-precision arithmetic found in most ALU hardware, which typically... )
	Signed	Unsigned	Signed	Unsigned	Signed	Unsigned	Signed	Unsigned	Signed	Unsigned
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...  (variable-width)	short short int	rowspan=2	short int	rowspan=2	int	rowspan=2	long int	rowspan=2	int		long long int
		bytes & bits
C C (programming language) C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....  (C99 C99 C99 is a modern dialect of the C programming language. It extends the previous version with new linguistic and library features, and helps implementations make better use of available computer hardware and compiler technology.-History:...  fixed-width)	int8_t	uint8_t	int16_t	uint16_t	int32_t	uint32_t	int64_t	uint64_t	int	unsigned int	rowspan=5
C++ C++ C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...  (C++11 fixed-width)
C C (programming language) C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....  (C99 C99 C99 is a modern dialect of the C programming language. It extends the previous version with new linguistic and library features, and helps implementations make better use of available computer hardware and compiler technology.-History:...  variable-width)	signed char	unsigned char	short	unsigned short	long	unsigned long	long long	unsigned long long
C++ C++ C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...  (C++11 variable-width)
Objective-C Objective-C Objective-C is a reflective, object-oriented programming language that adds Smalltalk-style messaging to the C programming language.Today, it is used primarily on Apple's Mac OS X and iOS: two environments derived from the OpenStep standard, though not compliant with it...	signed char	unsigned char	short	unsigned short	long	unsigned long	long long	unsigned long long	int or NSInteger	unsigned int or NSUInteger
C#	sbyte	byte	short	ushort	int	uint	long	ulong	rowspan=2 colspan=2	System.Numerics.BigInteger (.NET 4.0)
Java Java (programming language) Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...	byte			char					java.math.BigInteger
Go Go (programming language) Go is a compiled, garbage-collected, concurrent programming language developed by Google Inc.The initial design of Go was started in September 2007 by Robert Griesemer, Rob Pike, and Ken Thompson. Go was officially announced in November 2009. In May 2010, Rob Pike publicly stated that Go was being...	int8	uint8 or byte	int16	uint16	int32	uint32	int64	uint64	int	uint	big.Int
D D (programming language) The D programming language is an object-oriented, imperative, multi-paradigm, system programming language created by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is mainly influenced by that language, it is not a variant of C++...	byte	ubyte	short	ushort	int	uint	long	ulong			BigInt
Common Lisp Common Lisp Common Lisp, commonly abbreviated CL, is a dialect of the Lisp programming language, published in ANSI standard document ANSI INCITS 226-1994 , . From the ANSI Common Lisp standard the Common Lisp HyperSpec has been derived for use with web browsers...											bignum
Scheme
Pascal Pascal (programming language) Pascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...  (FPC Free Pascal Free Pascal Compiler is a free Pascal and Object Pascal compiler.In addition to its own Object Pascal dialect, Free Pascal supports, to varying degrees, the dialects of several other compilers, including those of Turbo Pascal, Delphi, and some historical Macintosh compilers... )	shortint	byte	smallint	word	longint	longword	int64	qword	integer	cardinal
Visual Basic Visual Basic Visual Basic is the third-generation event-driven programming language and integrated development environment from Microsoft for its COM programming model...		Byte	Integer		Long		colspan=2	rowspan=2 colspan=2	rowspan=1
Visual Basic .NET Visual Basic .NET Visual Basic .NET , is an object-oriented computer programming language that can be viewed as an evolution of the classic Visual Basic , which is implemented on the .NET Framework...	SByte		Short	UShort	Integer	UInteger	Long	ULong	System.Numerics.BigInteger (.NET 4.0)
Python Python (programming language) Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...  2.x	colspan=2	colspan=2	colspan=2	colspan=2	int		long
Python 3.x	colspan=2	colspan=2	colspan=2	colspan=2	colspan=2	int
S-Lang	colspan=2	colspan=2	colspan=2	colspan=2	colspan=2
Fortran Fortran Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...	INTEGER(KIND = n)		INTEGER(KIND = n)		INTEGER(KIND = n)		INTEGER(KIND = n)
PHP PHP PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...	colspan=2	colspan=2	int		colspan=2	colspan=2
Perl Perl Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...  5	colspan=2	colspan=2	colspan=2	colspan=2	colspan=2	Math::BigInt
Perl 6 Perl 6 Perl 6 is a major revision to the Perl programming language. It is still in development, as a specification from which several interpreter and compiler implementations are being written. It is introducing elements of many modern and historical languages. Perl 6 is intended to have many...	int8	uint8	int16	uint16	int32	uint32	int64	uint64	Int	colspan=2
Ruby Ruby (programming language) Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto...	colspan=2	colspan=2	colspan=2	colspan=2	Fixnum		Bignum
Windows PowerShell Windows PowerShell Windows PowerShell is Microsoft's task automation framework, consisting of a command-line shell and associated scripting language built on top of, and integrated with the .NET Framework...	colspan=2	colspan=2	colspan=2	colspan=2	colspan=2
OCaml	colspan=2	colspan=2	int32		int64		int or nativeint		open Big_int;; big_int
F#	sbyte	byte	int16	uint16		int32 or int	uint32	uint64	nativeint	unativeint	bigint
Standard ML Standard ML Standard ML is a general-purpose, modular, functional programming language with compile-time type checking and type inference. It is popular among compiler writers and programming language researchers, as well as in the development of theorem provers.SML is a modern descendant of the ML...		Word8.word	colspan=2	Int32.int	Word32.word	Int64.int	Word64.word	int	word	LargeInt.int or IntInf.int
Haskell Haskell (programming language) Haskell is a standardized, general-purpose purely functional programming language, with non-strict semantics and strong static typing. It is named after logician Haskell Curry. In Haskell, "a function is a first-class citizen" of the programming language. As a functional programming language, the...  (GHC Glasgow Haskell Compiler The Glorious Glasgow Haskell Compilation System, more commonly known as the Glasgow Haskell Compiler or GHC, is an open source native code compiler for the functional programming language Haskell. The lead developers are Simon Peyton Jones and Simon Marlow... )	«import Int» Int8	«import Word» Word8	«import Int» Int16	«import Word» Word16	«import Int» Int32	«import Word» Word32	«import Int» Int64	«import Word» Word64	Int	«import Word» Word	Integer
Eiffel Eiffel (programming language) Eiffel is an ISO-standardized, object-oriented programming language designed by Bertrand Meyer and Eiffel Software. The design of the language is closely connected with the Eiffel programming method...	INTEGER_8	NATURAL_8	INTEGER_16	NATURAL_16	INTEGER_32	NATURAL_32	INTEGER_64	NATURAL_64	INTEGER	NATURAL

The standard constants int shorts and int lengths can be used to determine how many shorts and longs can be usefully prefixed to short int and long int. The actually size of the short int, int and long int is available as constants short max int, max int and long max int etc.

Commonly used for characters.

The ALGOL 68, C and C++ languages do not specify the exact width of the integer types "short", "int", "long", and (C99, C++11) "long long", so they are implementation-dependent. In C and C++ "short", "long", and "long long" types are required to be at least 16, 32, and 64 bits wide, respectively, but can be more. The "int" type is required to be at least as wide as "short" and at most as wide as "long", and is typically the width of the word size on the processor of the machine (i.e. on a 32-bit machine it is often 32 bits wide; on 64-bit machines it is often 64 bits wide). C99 and C++11 also defines the "[u]intN_t" exact-width types in the stdint.h header. See C syntax#Integral types for more information.

Perl 5 does not have distinct types. Integers, floating point numbers, strings, etc. are all considered "scalars".

PHP has two arbitrary-precision libraries. The BCMath library just uses strings as datatype. The GMP library uses an internal "resource" type.

The value of "n" is provided by the SELECTED_INT_KIND intrinsic function.

ALGOL 68G

ALGOL 68G

ALGOL68G or Algol 68 Genie is a recent ALGOL 68 compiler-interpreter. ALGOL68G is a nearly full implementation of ALGOL 68 as defined by the Revised Report and also implements partial parametrisation, which is an extension of ALGOL 68. After successful parsing of an entire source program, the...

's run time option --precision "number" can set precision for long long int's to the required "number" significant digits. The standard constants long long int width and long long max int can be used to determine actual precision.

Floating point

Floating point

In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...

 

	Single precision	Double precision Double precision In computing, double precision is a computer number format that occupies two adjacent storage locations in computer memory. A double-precision number, sometimes simply called a double, may be defined to be an integer, fixed point, or floating point .Modern computers with 32-bit storage locations...	Processor dependent
ALGOL 68	real	long real	short real etc. & long long real etc.
C	float	double	rowspan=3
Objective-C
C++ (STL)
C#	float		rowspan=3
Java
Go	float32	float64
D	float	double	real
Common Lisp
Scheme
Pascal (Free Pascal)	single	double	real
Visual Basic	Single	Double	rowspan=2
Visual Basic .NET
Python	rowspan=2	float
JavaScript	Number
S-Lang
Fortran	REAL(KIND = n)
PHP		float
Perl
Perl 6	num32	num64	Num
Ruby		Float	rowspan=3
Windows PowerShell
OCaml		float
F#	float32
Standard ML		real
Haskell (GHC)	Float	Double
Eiffel	REAL_32	REAL_64

The standard constants real shorts and real lengths can be used to determine how many shorts and longs can be usefully prefixed to short real and long real. The actually size of the short real, real and long real is available as constants short max real, max real and long max real etc. With the constants short small real, small real and long small real available for each type's machine epsilon

Machine epsilon

Machine epsilon gives an upper bound on the relative error due to rounding in floating point arithmetic. This value characterizes computer arithmetic in the field of numerical analysis, and by extension in the subject of computational science...

.

declarations of single precision often are not honored

The value of "n" is provided by the SELECTED_REAL_KIND intrinsic function.

ALGOL 68G

ALGOL 68G

ALGOL68G or Algol 68 Genie is a recent ALGOL 68 compiler-interpreter. ALGOL68G is a nearly full implementation of ALGOL 68 as defined by the Revised Report and also implements partial parametrisation, which is an extension of ALGOL 68. After successful parsing of an entire source program, the...

's run time option --precision "number" can set precision for long long reals to the required "number" significant digits. The standard constants long long real width and long long max real can be used to determine actual precision.

Complex number

Complex number

A complex number is a number consisting of a real part and an imaginary part. Complex numbers extend the idea of the one-dimensional number line to the two-dimensional complex plane by using the number line for the real part and adding a vertical axis to plot the imaginary part...

s

	Integer	Single precision	Double precision	Half and Quadruple precision etc.
ALGOL 68		compl	long compl etc.	short compl etc. & long long compl etc.
C (C99)		float complex	double complex	rowspan=12
C++ (STL)		«std::»complex	«std::»complex
C#			System.Numerics.Complex (.Net 4.0)
Java
Go		complex64	complex128
D		cfloat	cdouble
Objective-C
Common Lisp
Scheme
Pascal
Visual Basic
Visual Basic .NET			System.Numerics.Complex (.Net 4.0)
Perl			Math::Complex
Perl 6		complex64	complex128	Complex
Python			complex	rowspan=12
JavaScript
S-Lang
Fortran		COMPLEX(KIND = n)
Ruby	Complex		Complex
Windows PowerShell
OCaml			Complex.t
F#			System.Numerics.Complex (.Net 4.0)
Standard ML
Haskell (GHC)		Complex.Complex Float	Complex.Complex Double
Eiffel

The value of "n" is provided by the SELECTED_REAL_KIND intrinsic function.

Other variable types

	Text		Boolean Boolean datatype In computer science, the Boolean or logical data type is a data type, having two values , intended to represent the truth values of logic and Boolean algebra...	Enumeration Enumerated type In computer programming, an enumerated type is a data type consisting of a set of named values called elements, members or enumerators of the type. The enumerator names are usually identifiers that behave as constants in the language...	Object Object (computer science) In computer science, an object is any entity that can be manipulated by the commands of a programming language, such as a value, variable, function, or data structure... /Universal Top type The top type in type theory, commonly abbreviated as top or by the down tack symbol , is the universal type—that type which contains every possible object in the type system of interest. The top type is sometimes called the universal supertype as all other types in any given type system are...
	Character Character (computing) In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....	String String (computer science) In formal languages, which are used in mathematical logic and theoretical computer science, a string is a finite sequence of symbols that are chosen from a set or alphabet....
ALGOL 68	char	string & bytes	bool & bits	- User defined
C (C99)	char wchar_t		bool	enum «name» {item1, item2, ... };	void Void type The void type, in several programming languages derived from C and Algol68, is the type for the result of a function that returns normally, but does not provide a result value to its caller. Usually such functions are called for their side effects, such as performing some task or writing to their...  *
C++ (STL)		«std::»string
Objective-C	unichar	NSString *	BOOL		id
C#	char	string	bool	enum name {item1, item2, ... }	object
Java		String	boolean		Object
Go	byte or int	string	bool	const ( item1 = iota item2 ... )	interface{}
D	char	string	bool	enum name {item1, item2, ... }	std.variant.Variant
Common Lisp
Scheme
Pascal (ISO)	char		boolean	(item1, item2, ...)
Object Pascal (Delphi)		string			variant
Visual Basic		String	Boolean	Enum name item1 item2 ... End Enum	Variant Variant type Variant is a data type in certain programming languages, particularly Visual Basic and C++ when using the Component Object Model.In Visual Basic the Variant data type is a tagged union that can be used to represent any other data type except fixed-length string type and...
Visual Basic .NET	Char				Object
Python		str	bool		object
JavaScript		String	Boolean		Object
S-Lang
Fortran	CHARACTER(LEN = *)	CHARACTER(LEN = :), allocatable	LOGICAL(KIND = n)		CLASS(*)
PHP		string	bool		object
Perl
Perl 6	Char	Str	Bool	enum name <item1 item2 ...> or enum name <<:item1(value) :item2(value) ...>>	Mu
Ruby		String	Object		Object
Windows PowerShell
OCaml	char	string	bool
F#				type name = item1 = value > item2 = value | ...	obj
Standard ML
Haskell (GHC)	Char	String	Bool
Eiffel	CHARACTER	STRING	BOOLEAN		ANY

specifically, strings of arbitrary length and automatically managed.

This language represents a boolean as an integer where false is represented as a value of zero and true by a non-zero value.

All values evaluate to either true or false. Everything in TrueClass evaluates to true and everything in FalseClass evaluates to false.

This language does not have a separate character type. Characters are represented as strings of length 1.

Enumerations in this language are algebraic types with only nullary constructors

The value of "n" is provided by the SELECTED_INT_KIND intrinsic function.

Array

Array data type

In computer science, an array type is a data type that is meant to describe a collection of elements , each selected by one or more indices that can be computed at run time by the program. Such a collection is usually called an array variable, array value, or simply array...

 

	fixed size array		dynamic size array
	one-dimensional array	multi-dimensional array	one-dimensional array	multi-dimensional array
ALGOL 68	[first:last]«modename» or simply: [size]«modename»	[first1:last1,first2:last2]«modename» or [first1:last1][first2:last2]«modename» etc.	flex[first:last]«modename» or simply: flex[size]«modename»	flex[first1:last1,first2:last2]«modename» or flex[first1:last1]flex[first2:last2]«modename» etc.
C (C99)
C++ (STL)	«std::»array<type, size>(C++11)		«std::»vector<type>
C#	type[]	type[,,...]	System.Collections.ArrayList or System.Collections.Generic.List<type>
Java	type[]	type[][]...	ArrayList or ArrayList<type>
D	type[size]	type[size1][size2]	type[]
Go	[size]type	[size1][size2]...type	vector.Vector
Objective-C	NSArray		NSMutableArray
JavaScript			Array
Common Lisp
Scheme
Pascal	array[first..last] of type	array[first1..last1] of array[first2..last2] ... of type or array[first1..last1, first2..last2, ...] of type
Object Pascal (Delphi)			array of type	array of array ... of type
Visual Basic
Visual Basic .NET			System.Collections.ArrayList or System.Collections.Generic.List(Of type)
Python			list
S-Lang
Fortran	type :: name(size)	type :: name(size1, size2,...)	type, ALLOCATABLE :: name(:)	type, ALLOCATABLE :: name(:,:,...)
PHP			array
Perl
Perl 6			Array[type] or Array of type
Ruby			Array
Windows PowerShell	type[]	type[,,...]
OCaml	type array	type array ... array
F#	type [] or type array	type [,,...]	System.Collections.ArrayList or System.Collections.Generic.List<type>
Standard ML	type vector or type array
Haskell (GHC)

In most expressions (except the sizeof and & operators), values of array types in C are automatically converted to a pointer of its first argument. Also C's arrays can not be described in this format. See C syntax#Arrays.

The C-like "type x[]" works in Java, however "type[] x" is the preferred form of array declaration.

Subranges are used to define the bounds of the array.

JavaScript's array are a special kind of object.

Other types

	Simple composite types		Algebraic data type Algebraic data type In computer programming, particularly functional programming and type theory, an algebraic data type is a datatype each of whose values is data from other datatypes wrapped in one of the constructors of the datatype. Any wrapped datum is an argument to the constructor... s	Unions Union (computer science) In computer science, a union is a value that may have any of several representations or formats; or a data structure that consists of a variable which may hold such a value. Some programming languages support special data types, called union types, to describe such values and variables...
	Records Record (computer science) In computer science, a record is an instance of a product of primitive data types called a tuple. In C it is the compound data in a struct. Records are among the simplest data structures. A record is a value that contains other values, typically in fixed number and sequence and typically indexed...	Tuple Tuple In mathematics and computer science, a tuple is an ordered list of elements. In set theory, an n-tuple is a sequence of n elements, where n is a positive integer. There is also one 0-tuple, an empty sequence. An n-tuple is defined inductively using the construction of an ordered pair...  expression
ALGOL 68	struct (modename «fieldname», ...);	Required types and operators can be user defined		union (modename, ...);
C (C99)	struct «name» {type name;...};	rowspan=2	rowspan=3	union {type name;...};
Objective-C
C++
C#	struct name {type name;...}			rowspan=3
Java
JavaScript
D	struct name {type name;...}		std.variant.Algebraic!(type,...)	union {type name;...}
Go	struct { «name» type ... }
Common Lisp		(cons val1 val2)
Scheme
Pascal	record name: type; ... end			record case type of value: (types); ... end
Visual Basic
Visual Basic .NET	Structure name Dim name As type ... End Structure
Python		«(»val1, val2, val3, ... «)»
S-Lang	struct {name [=value], ...}
Fortran	TYPE name type :: name ... END TYPE
PHP
Perl				rowspan=3
Perl 6
Ruby	OpenStruct.new({:name => value})
Windows PowerShell
OCaml	type name = {«mutable» name : type;...}	«(»val1, val2, val3, ... «)»	type name = Foo «of type» | Bar «of type» | ...	rowspan=4
F#
Standard ML	type name = {name : type,...}	(val1, val2, val3, ... )	datatype name = Foo «of type» > Bar «of type» | ...
Haskell	data Name = Constr {name :: type,...}		data Name = Foo «types» > Bar «types» | ...

Only classes are supported.

structs in C++ are actually classes, but POD objects are in fact records.

pair only

Although Perl doesn't have records, because Perl's type system allows different data types to be in an array, "hashes" (associative arrays) that don't have a variable index would effectively be the same as records.

Enumerations in this language are algebraic types with only nullary constructors

Variable and Constant Declarations

	variable	constant	type synonym
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...	modename name «:= initial_value»;	modename name = value;	mode Typedef typedef is a keyword in the C and C++ programming languages. The purpose of typedef is to assign alternative names to existing types, most often those whose standard declaration is cumbersome, potentially confusing, or likely to vary from one implementation to another.Under C convention , types... synonym = modename;
C (C99)	type name «= initial_value»;	enum{ name = value };	typedef Typedef typedef is a keyword in the C and C++ programming languages. The purpose of typedef is to assign alternative names to existing types, most often those whose standard declaration is cumbersome, potentially confusing, or likely to vary from one implementation to another.Under C convention , types... type synonym;
Objective-C
C++		const type name = value;
C#	type name «= initial_value»; or var name = value;	const type name = value; or readonly type name = value;	using synonym = type;
D	type name «= initial_value»; or auto name = value;	const type name = value; or immutable type name = value;	alias type synonym;
Java	type name «= initial_value»;	final type name = value;	rowspan=2
JavaScript	var name «= initial_value»;	const name = value;
Go	var name type «= initial_value» or name := initial_value	const name «type» = initial_value	type synonym type
Common Lisp	(defparameter name initial_value) or (defvar name initial_value) or (setf (symbol-value 'symbol) initial_value)	(defconstant name value)	(deftype synonym 'type)
Scheme	(define name initial_value)
Pascal	name: type «= initial_value»	name = value	synonym = type
Visual Basic	Dim name As type	Const name As type = value
Visual Basic .NET	Dim name As type«= initial_value»		Imports synonym = type
Python	name = initial_value		synonym = type
S-Lang	name = initial_value;		typedef struct {...} typename
Fortran	type name	type, PARAMETER :: name = value
PHP	$name = initial_value;	define("name", value); const name = value (5.3+)	rowspan=2
Perl	«my» $name «= initial_value»;	use constant name => value;
Perl 6	«my «type»» $name «= initial_value»;	«my «type»» constant name = value;	::synonym ::= type
Ruby	name = initial_value	Name = value	synonym = type
Windows PowerShell	«[type]» $name = initial_value
OCaml	let name «: type ref» = ref value	let name «: type» = value	type synonym = type
F#	let mutable name «: type» = value
Standard ML	val name «: type ref» = ref value	val name «: type» = value
Haskell		«name::type;» name = value	type Synonym = type
Forth	VARIABLE name (in some systems use value VARIABLE name instead)	value CONSTANT name

Pascal has declaration blocks. See Comparison of programming languages (basic instructions)#Functions.

Types are just regular objects, so you can just assign them.

In Perl, the "my" keyword scopes the variable into the block.

Technically, this does not declare name to be a mutable variable—in ML, all names can only be bound once; rather, it declares name to point to a "reference" data structure, which is a simple mutable cell. The data structure can then be read and written to using the ! and := operators, respectively.

Conditional statements

	if	else if	select case Switch statement In computer programming, a switch, case, select or inspect statement is a type of selection control mechanism that exists in most imperative programming languages such as Pascal, Ada, C/C++, C#, Java, and so on. It is also included in several other types of languages...	conditional expression
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...  & "brief form"	if condition then statements «else statements» fi	if condition then statements elif condition then statements fi	case switch in statements, statements«,... out statements» esac	( condition | valueIfTrue | valueIfFalse )
	statements «| statements» )	statements |: condition | statements )	statements,... «| statements» )
C (C99)	if (condition) {instructions} «else {instructions}»	if (condition) {instructions} else if (condition) {instructions} ... «else {instructions}»	switch (variable) { case case1: instructions «break;» ... «default: instructions» }	condition ? ?: In computer programming, ?: is a ternary operator that is part of the syntax for a basic conditional expression in several programming languages... valueIfTrue : valueIfFalse
Objective-C
C++ (STL)
D
Java
JavaScript
PHP
C#			switch (variable) { case case1: instructions; «jump statement;» ... «default: instructions; «jump statement;»» }
Windows PowerShell		if (condition) { instructions } elseif (condition) { instructions } ... «else { instructions }»	switch (variable) { case1 { instructions «break;» } ... «default { instructions }»}
Go	if condition {instructions} «else {instructions}»	if condition {instructions} else if condition {instructions} ... «else {instructions}» or switch { case condition: instructions ... «default: instructions» }	switch variable { case case1: instructions ... «default: instructions» }
Perl	if (condition) {instructions} «else {instructions}» or unless (notcondition) {instructions} «else {instructions}»	if (condition) {instructions} elsif (condition) {instructions} ... «else {instructions}» or unless (notcondition) {instructions} elsif (condition) {instructions} ... «else {instructions}»	use feature "switch"; ... given (variable) { when (case1) { instructions } ... «default { instructions }» }	condition ? valueIfTrue : valueIfFalse
Perl 6	if condition {instructions} «else {instructions}» or unless notcondition {instructions}	if condition {instructions} elsif condition {instructions} ... «else {instructions}	given variable { when case1 { instructions } ... «default { instructions }» }	condition ?? valueIfTrue !! valueIfFalse
Ruby	if condition instructions «else instructions» end	if condition instructions elsif condition instructions ... «else instructions» end	case variable when case1 instructions ... «else instructions» end	condition ? valueIfTrue : valueIfFalse
Common Lisp	(when condition instructions) or (unless condition instructions) or (if condition (progn instructions) «(progn instructions)»)	(cond (condition1 instructions) (condition2 instructions) ... «(t instructions)»)	(case expression (case1 instructions) (case2 instructions) ... «(otherwise instructions)»)	(if condition valueIfTrue valueIfFalse)
Scheme	(when conditioninstructions) or (if condition (begin instructions) «(begin instructions)»)	(cond (condition1 instructions) (condition2 instructions) ... «(else instructions)»)	(case (variable) ((case1) instructions) ((case2) instructions) ... «(else instructions)»)
Pascal	if condition then begin instructions end «else begin instructions end»	if condition then begin instructions end else if condition then begin instructions end ... «else begin instructions end»	case variable of case1: instructions ... «else: instructions» end
Visual Basic	If condition Then instructions «Else instructions» End If	If condition Then instructions ElseIf condition Then instructions ... «Else instructions» End If	Select Case variable Case case1 instructions ... «Case Else instructions» End Select	IIf IIf In computing, IIf is a function in several editions of the Visual Basic programming language, related languages such as ColdFusion Markup Language , and on spreadsheets that returns one of its three parameters based on the evaluation of one of the other parameters... (condition, valueIfTrue, valueIfFalse)
Visual Basic .NET				If(condition, valueIfTrue, valueIfFalse)
Python	if condition : instructions «else: instructions»	if condition : instructions elif condition : instructions ... «else: instructions»		valueIfTrue if condition else valueIfFalse (Python 2.5+)
S-Lang	if (condition) { instructions } «else { instructions }»	if (condition) { instructions } else if (condition) { instructions } ... «else { instructions }»	switch (variable) { case case1: instructions } { case case2: instructions } ...
Fortran	IF (condition) THEN instructions ELSE instructions ENDIF	IF (condition) THEN instructions ELSEIF (condition) THEN instructions ... ELSE instructions ENDIF	SELECT CASE(variable) CASE (case1) instructions ... CASE DEFAULT instructions END SELECT
Forth	condition IF instructions « ELSE instructions» THEN	condition IF instructions ELSE condition IF instructions THEN THEN	value CASE case OF instructions ENDOF case OF instructions ENDOF      default instructions ENDCASE	condition IF valueIfTrue ELSE valueIfFalse THEN
OCaml	if condition then begin instructions end «else begin instructions end»	if condition then begin instructions end else if condition then begin instructions end ... «else begin instructions end»	match value with pattern1 -> expression | pattern2 -> expression ... «| _ -> expression»	if condition then valueIfTrue else valueIfFalse
F#	if condition then instructions «else instructions»	if condition then instructions elif condition then instructions ... «else instructions»
Standard ML	if condition then «(»instructions «)» else «(» instructions «)»	if condition then «(»instructions «)» else if condition then «(» instructions «)» ... else «(» instructions «)»	case value of pattern1 => expression > pattern2 => expression ... «| _ => expression»
Haskell (GHC)	if condition then expression else expression or when condition (do instructions) or unless notcondition (do instructions)	> condition = expression | condition = expression | otherwise = expression	case value of { pattern1 -> expression; pattern2 -> expression; ... «_ -> expression» }
	if	else if	select case Switch statement In computer programming, a switch, case, select or inspect statement is a type of selection control mechanism that exists in most imperative programming languages such as Pascal, Ada, C/C++, C#, Java, and so on. It is also included in several other types of languages...	conditional expression

A single instruction can be written on the same line following the colon. Multiple instructions are grouped together in a block which starts on a newline (The indentation in required). The conditional expression syntax does not follow this rule.


This is pattern matching

Pattern matching

In computer science, pattern matching is the act of checking some sequence of tokens for the presence of the constituents of some pattern. In contrast to pattern recognition, the match usually has to be exact. The patterns generally have the form of either sequences or tree structures...

 and is similar to select case but not the same. It is usually used to deconstruct algebraic data type

Algebraic data type

In computer programming, particularly functional programming and type theory, an algebraic data type is a datatype each of whose values is data from other datatypes wrapped in one of the constructors of the datatype. Any wrapped datum is an argument to the constructor...

s.


In languages of the Pascal family, the semicolon is not part of the statement. It is a separator between statements, not a terminator.

Loop statements 

	while While loop In most computer programming languages, a while loop is a control flow statement that allows code to be executed repeatedly based on a given boolean condition. The while loop can be thought of as a repeating if statement....	do while Do while loop In most computer programming languages, a do while loop, sometimes just called a do loop, is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. Note though that unlike most languages, Fortran's do loop is actually analogous to the for loop.The...	for i = first to last For loop In computer science a for loop is a programming language statement which allows code to be repeatedly executed. A for loop is classified as an iteration statement....	foreach Foreach For each is a computer language idiom for traversing items in a collection. Foreach is usually used in place of a standard for statement. Unlike other for loop constructs, however, foreach loops usually maintain no explicit counter: they essentially say "do this to everything in this set",...
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...	«for index» «from first» «by increment» «to last» «while condition» do statements od			for key «to upb list» do «typename val=list[key];» statements od
	«while condition»     do statements od	«while statements; condition»     do statements od	«for index» «from first» «by increment» «to last» do statements od
C (C99)	while (condition) { instructions }	do { instructions } while (condition)	for («type» i = first; i <= last; ++i) { instructions }
Objective-C				for (type item in set) { instructions }
C++ (STL)				«std::»for_each(start, end, function) (C++11) for (type item : set) { instructions }
C#				foreach (type item in set) { instructions }
Java				for (type item : set) { instructions }
JavaScript			for (var i = first; i <= last; i++) { instructions }	for (var index in set) { instructions } or for each (var item in set) { instructions } (JS 1.6+)
PHP			foreach (range(first, last-1) as $i) { instructions } or for ($i = first; $i <= last; $i++) { instructions }	foreach (set as item) { instructions } or foreach (set as key => item) { instructions }
Windows PowerShell			for ($i = first; $i -le last; $i++) { instructions }	foreach (item in set) { instructions using item }
D			foreach (i; first ... last) { instructions }	foreach («type» item; set) { instructions }
Go	for condition { instructions }		for i := first; i <= last; i++ { instructions }	for key, item := range set { instructions }
Perl	while (condition) { instructions } or until (notcondition) { instructions }	do { instructions } while (condition) or do { instructions } until (notcondition)	for«each» «$i» (0 .. N-1) { instructions } or for ($i = first; $i <= last; $i++) { instructions }	for«each» «$item» (set) { instructions }
Perl 6	while condition { instructions } or until notcondition { instructions }	repeat { instructions } while condition or repeat { instructions } until notcondition	for first..last -> $i { instructions } or loop ($i = first; $i <= last; $i++) { instructions }	for set« -> $item» { instructions }
Ruby	while condition instructions end or until notcondition instructions end	begin instructions end while condition or begin instructions end until notcondition	for i in first...last instructions end or first.upto(last-1) { >i| instructions }	for item in set instructions end or set.each { >item| instructions }
Common Lisp	(loop while condition do instructions) or (do (notcondition) instructions)	(loop do instructions while condition)	(loop for i from first to last «by 1» do instructions) or (dotimes (i N) instructions) or (do ((i first (1+ i))) ((>= i last)) instructions)	(loop for item in set do instructions) or (dolist (item set) instructions) or (mapc function list) or (map 'type function sequence)
Scheme	(do (notcondition) instructions) or (let loop (if condition (begin instructions (loop))))	(let loop (instructions (if condition (loop))))	(do ((i first (+ i 1))) ((>= i last)) instructions) or (let loop ((i first)) (if (< i last) (begin instructions (loop (+ i 1)))))	(for-each (lambda (item) instructions) list)
Pascal	while condition do begin instructions end	repeat instructions until notcondition;	for i := first «step 1» to last do begin instructions end;
Visual Basic	Do While condition instructions Loop or Do Until notcondition instructions Loop	Do instructions Loop While condition or Do instructions Loop Until notcondition	For i = first To last «Step 1» instructions Next i	For Each item In set instructions Next item
Visual Basic .NET			For i «As type» = first To last «Step 1» instructions Next i	For Each item As type In set instructions Next item
Python	while condition : instructions «else: instructions»		for i in range(first, last): instructions «else: instructions»	for item in set: instructions «else: instructions»
S-Lang	while (condition) { instructions } «then optional-block»	do { instructions } while (condition) «then optional-block»	for (i = first; i < last; i++) { instructions } «then optional-block»	foreach item(set) «using (what)» { instructions } «then optional-block»
Fortran	DO WHILE (condition) instructions ENDDO	DO instructions IF (condition) EXIT ENDDO	DO I = first,last instructions ENDDO
Forth	BEGIN « instructions » condition WHILE instructions REPEAT	BEGIN instructions condition UNTIL	limit start DO instructions LOOP
OCaml	while condition do instructions done		for i = first to last-1 do instructions done	Array.iter (fun item -> instructions) array List.iter (fun item -> instructions) list
F#	while condition do instructions		for i = first to last-1 do instructions	for item in set do instructions or Seq.iter (fun item -> instructions) set
Standard ML	while condition do ( instructions )	colspan=2	Array.app (fn item => instructions) array app (fn item => instructions) list
Haskell (GHC)	colspan=2	Control.Monad.forM_ [0..N-1] (\i -> do instructions)	Control.Monad.forM_ list (\item -> do instructions)
Eiffel	from setup until condition loop instructions end

"step n" is used to change the loop interval. If "step" is omitted, then the loop interval is 1.

Exceptions

Exception handling

Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of exceptions, special conditions that change the normal flow of program execution....

 

	throw	handler	assertion
C (C99)	longjmp(state, exception);	switch (setjmp(state)) { case 0: instructions break; case exception: instructions ... }	assert(condition);
C++ (STL)	throw exception;	try { instructions } catch «(exception)» { instructions } ...
C#		try { instructions } catch «(exception)» { instructions } ... «finally { instructions }»	Debug.Assert(condition);
Java		try { instructions } catch (exception) { instructions } ... «finally { instructions }»	assert condition;
JavaScript		try { instructions } catch (exception) { instructions } «finally { instructions }»
D		try { instructions } catch (exception) { instructions } ... «finally { instructions }»	assert(condition);
PHP		try { instructions } catch (exception) { instructions } ...	assert(condition);
S-Lang		try { instructions } catch «exception» { instructions } ... «finally { instructions }»
Windows PowerShell		trap «[exception]» { instructions } ... instructions or try { instructions } catch «[exception]» { instructions } ... «finally { instructions }»	[Debug]::Assert(condition)
Objective-C	@throw exception;	@try { instructions } @catch (exception) { instructions } ... «@finally { instructions }»	NSAssert(condition, description);
Perl	die exception;	eval { instructions }; if ($@) { instructions }
Perl 6		try { instructions CATCH { when exception { instructions } ...}}
Ruby	raise exception	begin instructions rescue exception instructions ... «else instructions» «ensure instructions» end
Common Lisp	(error "exception") or (error (make-condition type arguments))	(handler-case (progn instructions) (exception instructions) ...) or (handler-bind (condition (lambda instructions «invoke-restart restart args»)) ...)	(assert condition) or (assert condition «(place) «error»») or (check-type var type)
Scheme (R6RS)	(raise exception)	(guard (con (condition instructions) ...) instructions)
Pascal	raise Exception.Create	try Except on E: exception do begin instructions end; end;
Visual Basic	colspan=2
Visual Basic .NET	Throw exception	Try instructions Catch «exception» «When condition» instructions ... «Finally instructions» End Try	Debug.Assert(condition)
Python	raise exception	try: instructions except «exception»: instructions ... «else: instructions» «finally: instructions»	assert condition
Fortran	colspan=3
Forth	code THROW	xt CATCH ( code or 0 )
OCaml	raise exception	try expression with pattern -> expression ...	assert condition
F#		try expression with pattern -> expression ... or try expression finally expression
Standard ML	raise exception «arg»	expression handle pattern => expression ...
Haskell (GHC)	throw exception or throwError expression	catch tryExpression catchExpression or catchError tryExpression catchExpression	assert condition expression

Common Lisp allows with-simple-restart, restart-case and restart-bind to define restarts for use with invoke-restart. Unhandled conditions may cause the implementation to show a restarts menu to the user before unwinding the stack.

Other control flow statements

	exit block(break)	continue	label Label (programming language) A label in a programming language is a sequence of characters that identifies a location within source code. In most languages labels take the form of an identifier, often followed by a punctuation character . In many high level programming languages the purpose of a label is to act as the...	branch (goto Goto goto is a statement found in many computer programming languages. It is a combination of the English words go and to. It performs a one-way transfer of control to another line of code; in contrast a function call normally returns control... )	return value from generator
ALGOL 68	value exit; ...	do statements; skip exit; label: statements od	label: ...	go to label; ... goto label; ... label; ...	yield(value) (Callback Callback (computer science) In computer programming, a callback is a reference to executable code, or a piece of executable code, that is passed as an argument to other code. This allows a lower-level software layer to call a subroutine defined in a higher-level layer....  - example)
C (C99)	break;	continue;	label:	goto label;	rowspan=4
Objective-C
C++ (STL)
D
C#					yield return value;
Java	break «label»;	continue «label»;		rowspan=2
JavaScript				yield value«;»
PHP	break «levels»;	continue «levels»;		goto label;
Perl	last «label»;	next «label»;
Perl 6
Go	break «label»	continue «label»		goto label
Common Lisp	(return) or (return-from block) or (loop-finish)		(tagbody tag ... tag ...)	(go tag)
Scheme
Pascal(ISO)	colspan=2	label:	goto label;	rowspan=4
Pascal(FPC)	break;			continue;
Visual Basic	Exit block		label:	GoTo label
Visual Basic .NET		Continue block
Python	break	continue	colspan=2	yield value
S-Lang	break;	continue;
Fortran	EXIT	CYCLE	label	GOTO label
Ruby	break	next
Windows PowerShell	break« label»	continue
OCaml	rowspan=4 colspan=4
F#
Standard ML
Haskell (GHC)

Pascal has declaration blocks. See Comparison of programming languages (basic instructions)#Functions.

label must be a number between 1 and 99999.

Functions

Subroutine

In computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....

 

See reflection

Reflection (computer science)

In computer science, reflection is the process by which a computer program can observe and modify its own structure and behavior at runtime....

 for calling and declaring functions by strings.

	calling a function	basic/void function	value-returning function	required main function
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...	foo«(parameters)»;	proc foo = «(parameters)» void Void type The void type, in several programming languages derived from C and Algol68, is the type for the result of a function that returns normally, but does not provide a result value to its caller. Usually such functions are called for their side effects, such as performing some task or writing to their... : ( instructions );	proc foo = «(parameters)» rettype: ( instructions ...; retvalue );
C (C99)	foo(«parameters»)	void Void type The void type, in several programming languages derived from C and Algol68, is the type for the result of a function that returns normally, but does not provide a result value to its caller. Usually such functions are called for their side effects, such as performing some task or writing to their...  foo(«parameters») { instructions }	type foo(«parameters») { instructions ... return value; }	«global declarations» int main(«int argc, char *argv[]») { instructions }
Objective-C
C++ (STL)
C#				static void Main(«string[] args») { instructions } or static int Main(«string[] args») { instructions }
Java				public static void main(String[] args) { instructions } or public static void main(String... Variadic function In computer programming, a variadic function is a function of indefinite arity, i.e., one which accepts a variable number of arguments. Support for variadic functions differs widely among programming languages....  args) { instructions }
D				int main(«char[][] args») { instructions} or int main(«string[] args») { instructions} or void main(«char[][] args») { instructions} or void main(«string[] args») { instructions}
JavaScript		function foo(«parameters») { instructions } or var foo = function («parameters») {instructions } or var foo = new Function («"parameter", ... ,"last parameter"» "instructions");	function foo(«parameters») { instructions ... return value; }
Go		func foo(«parameters») { instructions }	func foo(«parameters») type { instructions ... return value }	func main { instructions }
Common Lisp	(foo «parameters»)	(defun Defun defun is a macro in the Lisp family of programming languages that defines a function in the global environment that uses the form:...  foo («parameters») instructions) or (setf (symbol-function 'symbol) lambda)	(defun Defun defun is a macro in the Lisp family of programming languages that defines a function in the global environment that uses the form:...  foo («parameters») ... value)	rowspan=2
Scheme		(define (foo parameters) instructions) or (define foo (lambda Anonymous function In programming language theory, an anonymous function is a function defined, and possibly called, without being bound to an identifier. Anonymous functions are convenient to pass as an argument to a higher-order function and are ubiquitous in languages with first-class functions such as Haskell...  (parameters) instructions))	(define (foo parameters) instructions... return_value) or (define foo (lambda Anonymous function In programming language theory, an anonymous function is a function defined, and possibly called, without being bound to an identifier. Anonymous functions are convenient to pass as an argument to a higher-order function and are ubiquitous in languages with first-class functions such as Haskell...  (parameters) instructions... return_value))
Pascal	foo«(parameters)»	procedure foo«(parameters)»; «forward;» «label label declarations» «const constant declarations» «type type declarations» «var variable declarations» «local function declarations» begin instructions end;	function foo«(parameters)»: type; «forward;» «label label declarations» «const constant declarations» «type type declarations» «var variable declarations» «local function declarations» begin instructions; foo := value end;	program name; «label label declarations» «const constant declarations» «type type declarations» «var variable declarations» «function declarations» begin instructions end.
Visual Basic	Foo(«parameters»)	Sub Foo(«parameters») instructions End Sub	Function Foo(«parameters») As type instructions Foo = value End Function	Sub Main instructions End Sub
Visual Basic .NET			Function Foo(«parameters») As type instructions Return value End Function	Sub Main(«ByVal CmdArgs As String») instructions End Sub or Function Main(«ByVal CmdArgs As String») As Integer instructions End Function
Python	foo(«parameters»)	def foo(«parameters»): instructions	def foo(«parameters»): instructions return value
S-Lang	foo(«parameters» «;qualifiers»)	define foo («parameters») { instructions }	define foo («parameters») { instructions ... return value; }	public define slsh_main { instructions }
Fortran	foo («arguments») CALL sub_foo («arguments»)	SUBROUTINE sub_foo («arguments») instructions END SUBROUTINE	type FUNCTION foo («arguments») instructions ... foo = value END FUNCTION	PROGRAM main instructions END PROGRAM
Forth	«parameters» FOO	: FOO « stack effect comment: ( before -- ) » instructions ;	: FOO « stack effect comment: ( before -- after ) » instructions ;
PHP	foo(«parameters»)	function foo(«parameters») { instructions }	function foo(«parameters») { instructions ... return value; }	rowspan=6
Perl	foo(«parameters») or &foo«(parameters)»	sub foo { «my (parameters) = @_;» instructions }	sub foo { «my (parameters) = @_;» instructions... «return» value; }
Perl 6	foo(«parameters») or &foo«(parameters)»	«multi »sub foo(parameters) { instructions }	«our «type» »«multi »sub foo(parameters) { instructions... «return» value; }
Ruby	foo«(parameters)»	def foo«(parameters)» instructions end	def foo«(parameters)» instructions «return» value end
Windows PowerShell	foo« parameters»	function foo «(parameters)» { instructions }; or function foo { «param(parameters)» instructions }	function foo «(parameters)» { instructions … return value }; or function foo { «param(parameters)» instructions … return value }
OCaml	foo parameters	let «rec» foo parameters = instructions	let «rec» foo parameters = instructions... return_value
F#				[] let main args = instructions
Standard ML		fun foo parameters = ( instructions )	fun foo parameters = ( instructions... return_value )
Haskell		foo parameters = do instructions	foo parameters = return_value or foo parameters = do instructions return value	«main :: IO » main = do instructions
Eiffel	foo («parameters»)	foo («parameters») require preconditions do instructions ensure postconditions end	foo («parameters»): type require preconditions do instructions Result := value ensure postconditions end

Pascal requires "forward;" for forward declarations.

Eiffel allows the specification of an application's root class and feature.

In Fortran, function/subroutine parameters are called arguments (since PARAMETER is a language keyword); the CALL keyword is required for subroutines.

Type conversion

Type conversion

In computer science, type conversion, typecasting, and coercion are different ways of, implicitly or explicitly, changing an entity of one data type into another. This is done to take advantage of certain features of type hierarchies or type representations...

s

Where string is a signed decimal number:

	string to integer	string to long integer	string to floating point	integer to string	floating point to string
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...  with general, and then specific formats	With prior declarations and association of: string buf := "12345678.9012e34 "; file proxy; associate(proxy, buf);
	get(proxy, ivar);	get(proxy, livar);	get(proxy, rvar);	put(proxy, ival);	put(proxy, rval);
	getf(proxy, ($g$, ivar)); or getf(proxy, ($dddd$, ivar));	getf(proxy, ($g$, livar)); or getf(proxy, ($8d$, livar));	getf(proxy, ($g$, rvar)); or getf(proxy, ($8d.4dE2d$, rvar));	putf(proxy, ($g$, ival)); or putf(proxy, ($4d$, ival));	putf(proxy, ($g(width, places, exp)$, rval)); or putf(proxy, ($8d.4dE2d$, rval)); etc.
C (C99)	integer = atoi(string);	long = atol(string);	float = atof(string);	sprintf(string, "%i", integer);	sprintf(string, "%f", float);
Objective-C	integer = [string intValue];	long = [string longLongValue];	float = [string doubleValue];	string = [NSString stringWithFormat:@"%i", integer];	string = [NSString stringWithFormat:@"%f", float];
C++ (STL)	«std::»istringstream(string) >> number;			«std::»ostringstream o; o << number; string = o.str;
C++11	integer = «std::»stoi(string);	long = «std::»stol(string);	float = «std::»stof(string); double = «std::»stod(string);	string = «std::»to_string(number);
C#	integer = int.Parse(string);	long = long.Parse(string);	float = float.Parse(string); or double = double.Parse(string);	string = number.ToString;
D	integer = std.conv.to!int(string)	long = std.conv.to!long(string)	float = std.conv.to!float(string) or double = std.conv.to!double(string)	string = std.conv.to!string(number)
Java	integer = Integer.parseInt(string);	long = Long.parseLong(string);	float = Float.parseFloat(string); or double = Double.parseDouble(string);	string = Integer.toString(integer);	string = Float.toString(float); or string = Double.toString(double);
JavaScript	integer = parseInt(string);		float = parseFloat(string); or float = new Number (string) or float = Number (string) or float = string*1;	string = number.toString ; or string = new String (number); or string = String (number); or string = number+"";
Go	integer, error = strconv.Atoi(string)	long, error = strconv.Atoi64(string)	float, error = strconv.Atof(string)	string = strconv.Itoa(integer) or string = fmt.Sprint(integer)	string = strconv.Ftoa(float) or string = fmt.Sprint(float)
Common Lisp	(setf integer (parse-integer string))		(setf float (read-from-string string))	(setf string (princ-to-string number))
Scheme	(define number (string->number string))			(define string (number->string number))
Pascal	integer := StrToInt(string);		float := StrToFloat(string);	string := IntToStr(integer);	string := FloatToStr(float);
Visual Basic	integer = CInt(string)	long = CLng(string)	float = CSng(string) or double = CDbl(string)	string = CStr(number)
Visual Basic .NET
Python	integer = int(string)	long = long(string)	float = float(string)	string = str(number)
S-Lang	integer = atoi(string);	long = atol(string);	float = atof(string);	string = string(number);
Fortran	READ(string,format) number			WRITE(string,format) number
PHP	integer = intval(string); or integer = (int)string;		float = floatval(string); or float = (float)string;	string = "number"; or string = strval(number); or string = (string)number;
Perl	number = 0 + string;			string = "number";
Perl 6	number = +string;			string = ~number;
Ruby	integer = string.to_i or integer = Integer(string)		float = string.to_f or float = Float(string)	string = number.to_s
Windows PowerShell	integer = [int]string	long = [long]string	float = [float]string	string = [string]number; or string = "number"; or string = (number).ToString
OCaml	let integer = int_of_string string		let float = float_of_string string	let string = string_of_int integer	let string = string_of_float float
F#	let integer = int string	let integer = int64 string	let float = float string	let string = string number
Standard ML	val integer = Int.fromString string		val float = Real.fromString string	val string = Int.toString integer	val string = Real.toString float
Haskell (GHC)	number = read string			string = show number

JavaScript only uses floating point numbers so there are some technicalities.

Perl doesn't have separate types. Strings and numbers are interchangeable.

Standard Stream I/O

Standard streams

In Unix and Unix-like operating systems , as well as certain programming language interfaces, the standard streams are preconnected input and output channels between a computer program and its environment when it begins execution...

 

	read from	write to
	stdin	stdout	stderr
ALGOL 68 ALGOL 68 ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...	readf(($format$, x)); or getf(stand in, ($format$, x));	printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (($format$, x)); or putf(stand out, ($format$, x));	putf(stand error, ($format$, x));
C (C99)	scanf Scanf Scanf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for reading a string into an arbitrary number of varied data type parameter... (format, &x); or fscanf(stdin, format, &x);	printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... ( format, x); or fprintf(stdout, format, x);	fprintf(stderr, format, x );
Objective-C	data = SFileHandle fileHandleWithStandardInput] readDataToEndOfFile];	SFileHandle fileHandleWithStandardOutput] writeData:data];	SFileHandle fileHandleWithStandardError] writeData:data];
C++	«std::»cin Iostream iostream is a header file which is used for input/output in the C++ programming language. It is part of the C++ standard library. The name stands for Input/Output Stream. In C++ and its predecessor, the C programming language, there is no special syntax for streaming data input or output. Instead,...  >> x; or «std::»getline(«std::»cin, str);	«std::»cout Iostream iostream is a header file which is used for input/output in the C++ programming language. It is part of the C++ standard library. The name stands for Input/Output Stream. In C++ and its predecessor, the C programming language, there is no special syntax for streaming data input or output. Instead,...  << x;	«std::»cerr Iostream iostream is a header file which is used for input/output in the C++ programming language. It is part of the C++ standard library. The name stands for Input/Output Stream. In C++ and its predecessor, the C programming language, there is no special syntax for streaming data input or output. Instead,...  << x; or «std::»clog Iostream iostream is a header file which is used for input/output in the C++ programming language. It is part of the C++ standard library. The name stands for Input/Output Stream. In C++ and its predecessor, the C programming language, there is no special syntax for streaming data input or output. Instead,...  << x;
C#	x = Console.Read; or x = Console.ReadLine;	Console.Write(«format, »x); or Console.WriteLine(«format, »x);	Console.Error.Write(«format, »x); or Console.Error.WriteLine(«format, »x);
D	x = std.stdio.readln	std.stdio.write(x) or std.stdio.writeln(x) or std.stdio.writef(format, x) or std.stdio.writefln(format, x)	stderr.write(x) or stderr.writeln(x) or std.stdio.writef(stderr, format, x) or std.stdio.writefln(stderr, format, x)
Java	x = System.in.read; or x = new Scanner(System.in).nextInt; or x = new Scanner(System.in).nextLine;	System.out.print(x); or System.out.printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (format, x); or System.out.println(x);	System.err.print(x); or System.err.printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (format, x); or System.err.println(x);
Go	fmt.Scan(&x) or fmt.Scanf Scanf Scanf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for reading a string into an arbitrary number of varied data type parameter... (format, &x) or x = bufio.NewReader(os.Stdin).ReadString('\n')	fmt.Println(x) or fmt.Printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (format, x)	fmt.Fprintln(os.Stderr, x) or fmt.Fprintf(os.Stderr, format, x)
JavaScript Web Browser implementation Client-side JavaScript Client-side JavaScript is JavaScript that runs on the client-side. While JavaScript was originally created to run this way, the term was coined because the language is no longer limited to just client-side, since server-side JavaScript is now available.-Environment:The most common Internet media...		document.write(x)
JavaScript Active Server Pages Active Server Pages Active Server Pages , also known as Classic ASP or ASP Classic, was Microsoft's first server-side script engine for dynamically-generated Web pages. Initially released as an add-on to Internet Information Services via the Windows NT 4.0 Option Pack Active Server Pages (ASP), also known as Classic...		Response.Write(x)
JavaScript Windows Script Host Windows Script Host The Microsoft Windows Script Host is an automation technology for Microsoft Windows operating systems that provides scripting capabilities comparable to batch files, but with a greater range of supported features...	x = WScript.StdIn.Read(chars) or x = WScript.StdIn.ReadLine	WScript.Echo(x) or WScript.StdOut.Write(x) or WScript.StdOut.WriteLine(x)	WScript.StdErr.Write(x) or WScript.StdErr.WriteLine(x)
Common Lisp	(setf x (read-line))	(princ x) or (format t format x)	(princ x *error-output*) or (format *error-output* format x)
Scheme (R6RS)	(define x (read-line))	(display x) or (format #t format x)	(display x (current-error-port)) or (format (current-error-port) format x)
Pascal	read(x); or readln(x);	write(x); or writeln(x);	rowspan=2
Visual Basic	Input« prompt,» x	Print x or ? x
Visual Basic .NET	x = Console.Read or x = Console.ReadLine	Console.Write(«format, »x) or Console.WriteLine(«format, »x)	Console.Error.Write(«format, »x) or Console.Error.WriteLine(«format, »x)
Python 2.x	x = raw_input(«prompt»)	print x or sys.stdout.write(x)	print >> sys.stderr, x or sys.stderr.write(x)
Python 3.x	x = input(«prompt»)	print(x«, end=""»)	print(x«, end=""», file=sys.stderr)
S-Lang	fgets (&x, stdin)	fputs (x, stdout)	fputs (x, stderr)
Fortran	READ(*,format) variable names or READ(INPUT_UNIT,format) variable names	WRITE(*,format) expressions or WRITE(OUTPUT_UNIT,format) expressions	WRITE(ERROR_UNIT,format) expressions
Forth	buffer length ACCEPT ( # chars read ) KEY ( char )	buffer length TYPE char EMIT
PHP	$x = fgets(STDIN); or $x = fscanf(STDIN, format);	print x; or echo x; or printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (format, x);	fprintf(STDERR, format, x);
Perl	$x = <>; or $x = ;	print x; or printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string...  format, x;	print STDERR x; or printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string...  STDERR format, x;
Perl 6	$x = $*IN.get;	x.print or x.say	x.note or $*ERR.print(x) or $*ERR.say(x)
Ruby	x = gets	puts x or printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (format, x)	$stderr.puts(x) or $stderr.printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... (format, x)
Windows PowerShell	$x = Read-Host«« -Prompt» text»; or $x = [Console]::Read; or $x = [Console]::ReadLine	x; or Write-Output x; or echo x	Write-Error x
OCaml	let x = read_int or let str = read_line or Scanf.scanf Scanf Scanf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for reading a string into an arbitrary number of varied data type parameter... format (fun x ... -> ...)	print_int x or print_endline str or Printf.printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... format x ...	prerr_int x or prerr_endline str or Printf.eprintf format x ...
F#	let x = System.Console.ReadLine	printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... format x ... or printf Printf Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string... n format x ...	eprintf format x ... or eprintfn format x ...
Standard ML	val str = TextIO.inputLIne TextIO.stdIn	print str	TextIO.output (TextIO.stdErr, str)
Haskell (GHC)	x <- readLn or str <- getLine	print x or putStrLn str	hPrint stderr x or hPutStrLn stderr str

Algol 68 additionally as the "unformatted" transput routines: read, write, get and put.

gets(x) and fgets(x, length, stdin) read unformatted text from stdin. Use of gets is not recommended.

puts(x) and fputs(x, stdout) write unformatted text to stdout.

fputs(x, stderr) writes unformatted text to stderr

INPUT_UNIT, OUTPUT_UNIT, ERROR_UNIT are defined in the ISO_FORTRAN_ENV module.

Reading command-line arguments

	Argument values	Argument counts	Program name / Script name
C (C99)	argv[n]	argc	first argument
Objective-C
C++
C#	args[n]	args.Length	Assembly.GetEntryAssembly.Location;
Java		args.length
D			first argument
JavaScript Windows Script Host Windows Script Host The Microsoft Windows Script Host is an automation technology for Microsoft Windows operating systems that provides scripting capabilities comparable to batch files, but with a greater range of supported features...  implementation	WScript.Arguments(n)	WScript.Arguments.length
Go	os.Args[n]	len(os.Args)	first argument
Common Lisp
Scheme (R6RS)	(list-ref (command-line) n)	(length (command-line))	first argument
Pascal	ParamStr(n)	ParamCount	first argument
Visual Basic	Command		App.Path
Visual Basic .NET	CmdArgs(n)	CmdArgs.Length	[Assembly].GetEntryAssembly.Location
Python	sys.argv[n]	len(sys.argv)	first argument
S-Lang	__argv[n]	__argc	first argument
Fortran	DO i = 1,argc CALL GET_COMMAND_ARGUMENT (i,argv(i)) ENDDO	argc = COMMAND_ARGUMENT_COUNT	CALL GET_COMMAND_ARGUMENT (0,progname)
PHP	$argv[n]	$argc	first argument
Perl	$ARGV[n]	scalar(@ARGV)	$0
Perl 6	@*ARGS[n]	@*ARGS.elems	$PROGRAM_NAME
Ruby	ARGV[n]	ARGV.size	$0
Windows PowerShell	$args[n]	$args.Length	$MyInvocation.MyCommand.Name
OCaml	Sys.argv.(n)	Array.length Sys.argv	first argument
F#	args.[n]	args.Length	Assembly.GetEntryAssembly.Location
Standard ML	List.nth (CommandLine.arguments , n)	length (CommandLine.arguments )	CommandLine.name
Haskell (GHC)	do { args <- System.getArgs; return args !! n }	do { args <- System.getArgs; return length args }	System.getProgName

The command-line arguments in Visual Basic are not separated. A split function Split(string) is required for separating them.

Execution of commands

	Shell command	Execute program	Replace current program with new executed program Exec (operating system) The exec collection of functions of Unix-like operating systems cause the running process to be completely replaced by the program passed as an argument to the function...
C	system("command");		execl Exec (operating system) The exec collection of functions of Unix-like operating systems cause the running process to be completely replaced by the program passed as an argument to the function... (path, args); or execv Exec (operating system) The exec collection of functions of Unix-like operating systems cause the running process to be completely replaced by the program passed as an argument to the function... (path, arglist);
C++
Objective-C		[NSTask launchedTaskWithLaunchPath:(NSString *)path arguments:(NSArray *)arguments];
C#		System.Diagnostics.Process.Start(path, argstring);
F#
Go		exec.Run(path, argv, envv, dir, exec.DevNull, exec.DevNull, exec.DevNull)	os.Exec(path, argv, envv)
Visual Basic	Interaction.Shell(command «, WindowStyle» «, isWaitOnReturn»)
Visual Basic .NET	Microsoft.VisualBasic.Interaction.Shell(command «, WindowStyle» «, isWaitOnReturn»)	System.Diagnostics.Process.Start(path, argstring)
D	std.process.system("command");		std.process.execv(path, arglist);
Java		Runtime.exec(command); or new ProcessBuilder(command).start;
JavaScript Windows Script Host Windows Script Host The Microsoft Windows Script Host is an automation technology for Microsoft Windows operating systems that provides scripting capabilities comparable to batch files, but with a greater range of supported features... implementation	WScript.CreateObject ("WScript.Shell").Run(command «, WindowStyle» «, isWaitOnReturn»);
Common Lisp	(shell command)
Scheme	(system command)
Pascal	system(command);
OCaml	Sys.command command, Unix.open_process_full command env (stdout, stdin, stderr),...	Unix.create_process prog args new_stdin new_stdout new_stderr, ...	Unix.execv prog args or Unix.execve prog args env
Standard ML	OS.Process.system command	Unix.execute (path, args)	Posix.Process.exec (path, args)
Haskell (GHC)	System.system command	System.Process.runProcess path args ...	Posix.Process.executeFile path True args ...
Perl	system(command) or $output = `command`		exec(path, args)
Ruby	system(command) or output = `command`		exec(path, args)
PHP	system(command) or $output = `command` or exec(command) or passthru(command)
Python	os.system(command) or subprocess.Popen(command)		os.execv(path, args)
S-Lang	system(command)
Fortran	CALL SYSTEM (command, status) or status = SYSTEM (command)
Windows PowerShell	[Diagnostics.Process]::Start(command)	«Invoke-Item »program arg1 arg2 …

Compiler-dependent extension.

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.