Comparison of programming languages (basic instructions)

From Wikipedia, the free encyclopedia

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (February 2009)

This article is part of the Programming Language Comparison series.
General Comparison
Basic Syntax
Basic Instructions
Arrays
Associative arrays
String Operations
String Functions
List comprehension
Object-oriented programming
Object-oriented constructors
Database access
Database RDBMS
Evaluation strategy
List of "hello world" programs
Comparison of ALGOL 68 and C++
Compatibility of C and C++
Comparison of Pascal and Borland Delphi
Comparison of Pascal and C
Comparison of Java and C++
Comparison of Java and C#
Comparison of C# and Visual Basic .NET
Comparison of ABAP and Java
This box: view • talk • edit

Comparison of programming languages is a common topic of discussion among software engineers. Basic instructions of several programming languages are compared here.

Contents 1 Type identifiers 1.1 Integers 1.2 Floating point 1.3 Complex numbers 1.4 Other variable types 2 Derived types 2.1 Array 2.2 Other types 3 Declarations 4 Control flow 4.1 Conditional statements 4.2 Loop statements 4.3 Exceptions 4.4 Other control flow statements 5 Functions 6 Type conversions 7 Standard Input and Standard Output 8 Reading command-line arguments 9 Execution of commands 10 References

[edit] Type identifiers

[edit] Integers

	8 bit (byte)		16 bit (short integer)		32 bit		64 bit (long integer)		Word size		Arbitrarily precise (bignum)
	Signed	Unsigned	Signed	Unsigned	Signed	Unsigned	Signed	Unsigned	Signed	Unsigned
C (C99 fixed-width)	int8_t	uint8_t	int16_t	uint16_t	int32_t	uint32_t	int64_t	uint64_t	int	unsigned int	N/A
C (C99 variable-width)	signed char	unsigned char	short[a]	unsigned short[a]	long[a]	unsigned long[a]	long long[a]	unsigned long long[a]
C++
Objective-C	signed char	unsigned char	short[a]	unsigned short[a]	long[a]	unsigned long[a]	long long[a]	unsigned long long[a]	int or NSInteger	unsigned int or NSUInteger
C#	sbyte	byte	short	ushort	int	uint	long	ulong	N/A
Java	byte;	N/A		char[b]		N/A		N/A			java.math.BigInteger
Common Lisp
Scheme
Pascal (FPC)	shortint	byte	smallint	word	longint	longword	int64	qword	integer	cardinal	N/A
Visual Basic	N/A	Byte	Integer	N/A	Long	N/A	N/A		N/A		N/A
Visual Basic .NET	SByte		Short	UShort	Integer	UInteger	Long	ULong
Python 2.x	N/A		N/A		int	N/A	N/A		N/A		long
Python 3.x	N/A		N/A		N/A		N/A		N/A		int
JavaScript	N/A		N/A		N/A		N/A		N/A		N/A
S-Lang	N/A		N/A		N/A		N/A		N/A		N/A
FORTRAN 77	N/A		INTEGER	N/A	N/A		N/A
PHP	N/A		N/A		int	N/A	N/A		N/A		[d]
Perl 5	N/A[c]		N/A[c]		N/A[c]		N/A[c]		N/A[c]		Math::BigInt
Ruby	N/A		N/A		Fixnum	N/A	N/A		N/A		Bignum
Windows PowerShell	N/A		N/A		N/A		N/A		N/A		N/A
OCaml	N/A		N/A		int32	N/A	int64	N/A	int or nativeint		open Big_int;; big_int
F#	sbyte	byte	int16	uint16	int32 or int	uint32		uint64	nativeint	unativeint	bigint
Standard ML	N/A	Word8.word	N/A		Int32.int	Word32.word	Int64.int	Word64.word	int	word	LargeInt.int or IntInf.int
Haskell (GHC)	«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

^a  The C and C++ languages do not specify the exact width of the integer types "short", "int", "long", and (C99, C++0x) "long long", so they are implementation-dependent. The "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 also defines the "[u]intN_t" exact-width types in the stdint.h header. See C syntax#Integral types for more information.
^b  Commonly used for characters.
^c  Perl 5 does not have distinct types. Integers, floating point numbers, strings, etc. are all considered "scalars".
^d  PHP has two arbitrary-precision libraries. The BCMath library just uses strings as datatype. The GMP library uses an internal "resource" type.

[edit] Floating point

	Single precision	Double precision	Processor dependent
C	float[a]	double	N/A[a]
Objective-C
C++ (STL)
C#	float		N/A
Java
Common Lisp
Scheme
Pascal (Free Pascal)	single	double	real
Visual Basic	Single	Double	N/A
Visual Basic .NET
Python	N/A	float
JavaScript		Number[1]	N/A
S-Lang
FORTRAN 77	REAL	DOUBLE PRECISION
PHP		float
Perl
Ruby	N/A	Float	N/A
Windows PowerShell
OCaml	N/A	float
F#	float32
Standard ML	N/A	real
Haskell (GHC)	Float	Double

^a  declarations of single precision often are not honored

[edit] Complex numbers

	Integer	Single precision	Double precision
C (C99) [2]	N/A	float complex	double complex
C++ (STL)	N/A	«std::»complex<float>	«std::»complex<double>
C#	N/A	N/A
Java	N/A	N/A
Objective-C	N/A	N/A
Common Lisp
Scheme
Pascal	N/A	N/A
Visual Basic	N/A	N/A
Visual Basic .NET	N/A	N/A
Perl
Python
JavaScript	N/A	N/A
S-Lang	N/A	N/A
FORTRAN 77		COMPLEX
Ruby	N/A	N/A
Windows PowerShell	N/A	N/A
OCaml	N/A
F#
Standard ML	N/A	N/A
Haskell (GHC)

[edit] Other variable types

	Text		Boolean	Object/Universal
	Character	String[a]
C (C99)	char	N/A	bool[b]	void *
C++ (STL)		«std::»string
C#		string	bool	object
Java		String	boolean	Object
Objective-C	unichar	NSString *	BOOL	id
Common Lisp
Scheme
Pascal (ISO)	char	N/A	boolean	N/A
Object Pascal (Delphi)		string		variant
Visual Basic	N/A	String	Boolean	Variant
Visual Basic .NET	Char			Object
Python	N/A[d]	str	bool	object
JavaScript	N/A[d]	String	Boolean	Object
S-Lang
FORTRAN 77	CHARACTER*1	N/A	LOGICAL	N/A
PHP	N/A[d]	string	bool	object
Perl	[d]
Ruby	N/A[d]	String	Object[c]	Object
Windows PowerShell
OCaml	char	string	bool	N/A
F#				obj
Standard ML				N/A
Haskell (GHC)	Char	String	Bool	N/A

^a  specifically, strings of arbitrary length and automatically managed.
^b  This language represents a boolean as an integer where false is represented as a value of zero and true by a non-zero value.
^c  All values evaluates to either true or false. Everything in TrueClass evaluates to true and everything in FalseClass evaluates to false.
^d This language does not have a separate character type. Characters are represented as strings of length 1.

[edit] Derived types

[edit] Array

	fixed size array		dynamic size array
	one-dimensional array	multi-dimensional array	one-dimensional array	multi-dimensional array
C (C99)	[a]	[a]
C++ (STL)			«std::»vector<type>
C#	type[size]	type[size1, size2,...]	System.Collections.ArrayList or System.Collections.Generic.List<type>
Java	type[size][b]	type[size1][size2]...[b]	ArrayList or ArrayList<type>
Objective-C			NSMutableArray
JavaScript	N/A	N/A	Array[d]
Common Lisp
Scheme
Pascal	array[first..last] of type[c]	array[first1..last1] of array[first2..last2] ... of type [c] or array[first1..last1, first2..last2, ...] of type [c]
Visual Basic
Visual Basic .NET			System.Collections.ArrayList or System.Collections.Generic.List(Of type)
Python			list
S-Lang
FORTRAN 77
PHP
Perl
Ruby			Array
Windows PowerShell
OCaml
OCaml	type [] or type array	type [,,...]	System.Collections.ArrayList or System.Collections.Generic.List<type>
Standard ML
Haskell (GHC)

^a 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.
^b  The C-like "type x[]" works in Java, however "type[] x" is the preferred form of array declaration.
^c  Subranges are use to define the bounds of the array.
^d  JavaScript's array are a special kind of object.

[edit] Other types

	Simple composite types			Algebraic data types	Unions
	Records	Tuple expression	Enumeration
C (C99)	struct «name» {type name;...};	N/A	enum «name» {item1, item2, ... };	N/A	union {type name;...};
Objective-C
C++	N/A[a][b]	N/A
C#	struct name {type name;...}		enum name {item1, item2, ... }		N/A
Java	N/A[a]
JavaScript		N/A
Common Lisp		(cons val1 val2)[c]
Scheme	N/A
Pascal	record name: type; ... end	N/A	(item1, item2, ...)	N/A	record case type of value: type; ... end
Visual Basic			Enum name item1 item2 ... End Enum
Visual Basic .NET	Structure name Dim name As type ... End Structure
Python	N/A[a]	«(»val1, val2, val3, ... «)»			N/A
S-Lang	struct {name [=value], ...}
FORTRAN 77
PHP	N/A[a]
Perl	N/A[d]				N/A
Ruby	N/A[a]
Windows PowerShell
OCaml	type name = {«mutable» name : type;...}	«(»val1, val2, val3, ... «)»	N/A[e]	type name = Foo «of type» | Bar «of type» | ...
F#			type name = item1 = value | item2 = value | ...
Standard ML	type name = {name : type,...}	(val1, val2, val3, ... )	N/A[e]	datatype name = Foo «of type» | Bar «of type» | ...
Haskell	data Name = Constr {name :: type,...}			data Name = Foo «types» | Bar «types» | ...

^a  Only classes are supported.
^b  structs in C++ are actually classes.
^c  pair only
^d  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.
^e  Enumerations in this language are algebraic types with only nullary constructors

[edit] Declarations

	variable	constant	type synonym
C (C99)	type name «= initial_value»;	enum{ name = value };	typedef type synonym;
Objective-C
C++		const type name = value;
C#			using synonym = type;
Java		final type name = value;	N/A
JavaScript	var name «= initial_value»;	const name = value;
Common Lisp	(defparameter name initial_value)	(defconstant name value)	(deftype synonym () 'type)
Scheme	(define name initial_value)
Pascal[a]	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	x = initial_value	N/A	synonym = type[b]
S-Lang	x = initial_value;		typedef struct {...} typename
FORTRAN 77	type name
PHP	$x = initial_value;	define("name", "value");	N/A
Perl	«my »$x = initial_value;[c]	use constant name => value;
Ruby	x = initial_value	N/A
Windows PowerShell	«[type]» $name = initial_value
OCaml		let name «: type» = value	type synonym = type
F#	let mutable name «: type» = value
Standard ML		val name «: type» = value
Haskell		«name::type;» name = value	type Synonym = type

^a  Pascal has declaration blocks. See Comparison of programming languages (basic instructions)#Functions.
^b Types are just regular objects in Python, so you can just assign them.
^c  In Perl, the "my" keyword scopes the variable into the block.

[edit] Control flow

Statements in guillemets (« … ») are optional.

[edit] Conditional statements

	if	else if	select case	conditional expression
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 ? valueIfTrue : valueIfFalse
Objective-C
C++ (STL)
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 }»}
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
Ruby	if condition instructions «else instructions» end	if condition instructions elsif condition instructions ... «else instructions» end	case variable when case1 instructions ... «else instructions» end
Common Lisp	(when condition instructions) or (if condition (progn instructions) «(progn instructions)»)	(cond (condition1 instructions) (condition2 instructions) ... «(t instructions)»)	(case (variable) (case1 instructions) (case2 instructions) ... «(t instructions)»)	(if condition valueIfTrue valueIfFalse)
Scheme	(when condition instructions) 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(condition, valueIfTrue, valueIfFalse)
Visual Basic .NET				If(condition, valueIfTrue, valueIfFalse)
Python	if condition : Tab ⇆ instructions «else: Tab ⇆ instructions»	if condition : Tab ⇆ instructions elif condition : Tab ⇆ instructions ... «else: Tab ⇆ instructions»	N/A	valueIfTrue if condition else valueIfFalse
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 77	IF condition THEN instructions «ELSE instructions» ENDIF	IF condition THEN instructions ELSEIF condition THEN instructions ... «ELSE instructions» ENDIF	index = f(variable)      GOTO ( c1, c2, ... cn) index ... c1  instructions
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»[a]	if condition then valueIfTrue else valueIfFalse
F#	if condition then Tab ⇆ instructions «else Tab ⇆ instructions»	if condition then Tab ⇆ instructions elif condition then Tab ⇆ instructions ... «else Tab ⇆ 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»[a]
Haskell (GHC)	when condition (do instructions) or unless notcondition (do instructions)	N/A	case value of { pattern1 -> expression; pattern2 -> expression; ... «_ -> expression» }[a]
	if	else if	select case	conditional expression

^a  This is pattern matching and is similar to select case but not the same. It is usually used to deconstruct algebraic data types.

[edit] Loop statements

The bold is the literal code. The non-bold is interpreted by the reader. Statements in guillemets (« … ») are optional.

	while	do while	for i = first to last	foreach
C (C99)	while (condition) { instructions }	do { instructions } while (condition)	for («type» i = first; i <= last; ++i) { instructions }	N/A
Objective-C				for (type item in set) { instructions }
C++ (STL)				«std::»for_each(start, end, function)
C#				foreach (type item in set) { instructions }
Java				for (type item : set) { instructions }
JavaScript			for (var i = first; i <= last; i++) { instructions }	for (var property in object) { instructions }
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; $i++) { instructions }	foreach (item in set) { instructions using item }
Perl	while (condition) { instructions } or until (notcondition) { instructions }	do { instructions } while (condition) or do { instructions } until (notcondition)	for«each» «$i» (0 .. N-1) { instructions } or for ($i = first; $i <= last; $i++) { instructions }	for«each» «$item» (set) { instructions }
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 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)
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;[a]	N/A
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[a]	For Each item As type In set instructions Next item
Python	while condition : Tab ⇆ instructions «else: Tab ⇆ instructions»	N/A	for i in range(first, last): Tab ⇆ instructions «else: Tab ⇆ instructions»	for item in set: Tab ⇆ instructions «else: Tab ⇆ 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 77	N/A		DO nnnn I = first,last instructions nnnn CONTINUE	N/A
Forth	BEGIN « instructions » condition WHILE instructions REPEAT	BEGIN instructions condition UNTIL	limit start DO instructions LOOP	N/A
OCaml	while condition do instructions done	N/A	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 Tab ⇆ instructions	N/A	for i = first to last-1 do Tab ⇆ instructions	for item in set do Tab ⇆ instructions or Seq.iter (fun item -> instructions) set
Standard ML	while condition do ( instructions )	N/A		Array.app (fn item => instructions) array app (fn item => instructions) list
Haskell (GHC)	N/A		Control.Monad.forM_ [0..N-1] (\i -> do instructions)	Control.Monad.forM_ list (\item -> do instructions)

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

[edit] Exceptions

The bold is the literal code. The non-bold is interpreted by the reader. Statements in guillemets (« … ») are optional.

	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 }»	?
PHP		try { instructions } catch (exception) { instructions } ...	assert(condition);
S-Lang		try { instructions } catch «exception» { instructions } ... «finally { instructions }»	?
Windows PowerShell		trap «[exception]» { instructions } ... 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 }	?
Ruby	raise exception	begin instructions rescue exception instructions ... «else instructions» «ensure instructions» end
Common Lisp	(error exception)	(handler-case (progn instructions) (exception instructions) ...)	?
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	N/A		?
Visual Basic .NET	Throw exception	Try instructions Catch «exception» «When condition» instructions ... «Finally instructions» End Try	Debug.Assert(condition)
Python	raise exception	try: Tab ⇆ instructions except «exception»: Tab ⇆ instructions ... «else: Tab ⇆ instructions» «finally: Tab ⇆ instructions»	assert condition
FORTRAN 77	N/A		?
Forth	code THROW	xt CATCH ( code or 0 )	N/A
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

[edit] Other control flow statements

	exit block(break)	continue	label	branch (goto)	return value from generator
C (C99)	break;	continue;	label:	goto label;	N/A
Objective-C
C++ (STL)
C#					yield return value;
Java	break «label»;	continue «label»;		N/A
JavaScript					yield value«;»
PHP	break «levels»;	continue «levels»;	N/A	goto ;	return() ;
Perl	last «label»;	next «label»;	label:	goto label;
Common Lisp	(return) or (return-from block)			(go tag)
Scheme
Pascal(ISO)	N/A		label:[a]	goto label;	N/A
Pascal(FPC)	break;	continue;
Visual Basic	Exit block	N/A	label:	GoTo label
Visual Basic .NET		Continue block
Python	break	continue	N/A		yield value
S-Lang	break;	continue;
FORTRAN 77	N/A		a number in columns 1 to 5	GOTO label	N/A
Ruby	break	next
Windows PowerShell	break« label»	continue
OCaml	N/A
F#
Standard ML
Haskell (GHC)

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

[edit] Functions

Statements in guillemets (« … ») are optional. See reflection for calling and declaring functions by strings.

	calling a function	basic/void function	value-returning function	required main function
C (C99)	foo(«parameters»);	void foo(«parameters») { instructions }	type foo(«parameters») { instructions ... return value; }	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... 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; }	N/A
Common Lisp	(foo «parameters»)	(defun foo (parameters) instructions)	(defun foo (parameters) instructions... return_value)
Scheme		(define (foo parameters) instructions) or (define foo (lambda (parameters) instructions))	(define (foo parameters) instructions... return_value) or (define foo (lambda (parameters) instructions... return_value))
Pascal	foo«(parameters)»	procedure foo«(parameters)»; «forward;»[a] «label label declarations» «const constant declarations» «type type declarations» «var variable declarations» «local function declarations» begin instructions end;	function foo«(parameters)»: type; «forward;»[a] «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»): Tab ⇆ instructions	def foo(«parameters»): Tab ⇆ instructions Tab ⇆ return value	N/A
S-Lang	foo(«parameters» «;qualifiers»)	define foo («parameters») { instructions }	define foo («parameters») { instructions ... return value; }	public define slsh_main () { instructions }
FORTRAN 77		SUBROUTINE FOO«(parameters)» instructions END	type FUNCTION FOO«(parameters)» instructions FOO = value END	PROGRAM main
Forth	«parameters» FOO	: FOO « stack effect comment: ( before -- after ) » instructions  ;	N/A	N/A
PHP	foo(«parameters»)	function foo(«parameters») { instructions }	function foo(«parameters») { instructions ... return value; }	N/A
Perl	foo(«parameters») or &foo«(parameters)»	sub foo { «my (parameters) = @_;» instructions }	sub foo { «my (parameters) = @_;» instructions... «return» value; }
Ruby	foo«(parameters)»	def foo«(parameters)» instructions end	def foo«(parameters)» instructions «return» value end
Windows PowerShell		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#				[<EntryPoint>] let main args = instructions
Standard ML		fun foo parameters = ( instructions )	fun foo parameters = ( instructions... return_value )
Haskell		foo parameters = do Tab ⇆ instructions	foo parameters = return_value or foo parameters = do Tab ⇆ instructions Tab ⇆ return value	«main :: IO ()» main = do instructions

^a  Pascal requires "forward;" for forward declarations.

[edit] Type conversions

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
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#	integer = int.Parse(string);	long = long.Parse(string);	float = float.Parse(string); or double = double.Parse(string);	string = number.ToString();
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[a]	integer = parseInt(string);		float = parseFloat(string); or float = new Number (string) or float = string*1;	N/A	string = number.toString (); or string = new String (number); or string = number+"";
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 77	READ(string,format) integer	N/A	READ(string,format) float	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[b]	number = 0 + string;			string = "$number";
Ruby	integer = string.to_i		float = string.to_f	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

^a  JavaScript only uses floating point numbers so there are some technicalities.^[1]
^b  Perl doesn't have separate types. Strings and numbers are interchangeable.

[edit] Standard Input and Standard Output

	read from	write to
	stdin	stdout	stderr
C (C99)	scanf(format, &x); or fscanf(stdin, format, &x); [a]	printf( format, x); or fprintf(stdout, format, x); [b]	fprintf(stderr, format, x );[c]
Objective-C
C++	«std::»cin >> x; or «std::»getline(«std::»cin, str);	«std::»cout << x;	«std::»cerr << x; or «std::»clog << 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);
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(format, x); or System.out.println(x);	System.err.print(x); or System.err.printf(format, x); or System.err.println(x);
JavaScript Web Browser implementation		document.write(x)
JavaScript Active Server Pages		Response.Write(x)
JavaScript Windows Script Host	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);	N/A
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 77	READ(5,format) variable names	WRITE(6,format) expressions	N/A
Forth	buffer length ACCEPT ( # chars read ) KEY ( char )	buffer length TYPE char EMIT	N/A
PHP	$x = fgets(STDIN); or $x = fscanf(STDIN, format);	print x; or echo x; or printf(format, x);	fprintf(STDERR, format, x);
Perl	$x = <>; or $x = <STDIN>;	print x; or printf format, x;	print STDERR x; or printf STDERR format, x;
Ruby	x = gets	puts x or printf(format, x)	$stderr.puts(x) or $stderr.printf(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 format (fun x ... -> ...)	print_int x or print_endline str or Printf.printf format x ...	prerr_int x or prerr_endline str or Printf.eprintf format x ...
F#	let x = System.Console.ReadLine()	printf format x ... or printfn 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

^a  gets(x) and fgets(x, length, stdin) read unformatted text from stdin. Use of gets is not recommended.
^b  puts(x) and fputs(x, stdout) write unformatted text to stdout.
^c  fputs(x, stderr) writes unformatted text to stderr

[edit] 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
JavaScript Windows Script Host implementation	WScript.Arguments(n)	WScript.Arguments.length	?
Common Lisp	?	?	?
Scheme (R6RS)	(list-ref (command-line) n)	(length (command-line))	first argument
Pascal	ParamStr(n)	ParamCount	first argument
Visual Basic	Command	N/A	?
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 77	N/A		?
PHP	$argv[n]	$argc	first argument
Perl	$ARGV[n]	scalar(@ARGV)	$0
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

[edit] Execution of commands

	Shell command	Execute program
C	system("command");	execl(path, args); or execv(path, arglist);
C++
C#		System.Diagnostics.Process.Start(path, argstring);
F#
Visual Basic	Interaction.Shell(command «, WindowStyle» «, isWaitOnReturn»)
Visual Basic .NET	Microsoft.VisualBasic.Interaction.Shell(command «, WindowStyle» «, isWaitOnReturn»)	System.Diagnostics.Process.Start(path, argstring)
Java	Runtime.exec(command); or new ProcessBuilder(command).start();
JavaScript Windows Script Host implementation	WScript.CreateObject ("WScript.Shell").Run(command «, WindowStyle» «, isWaitOnReturn»);
Common Lisp	(shell command)
Scheme	(system command)
Pascal	system(command);
OCaml	Sys.command command
Standard ML	OS.Process.system command
Haskell (GHC)	System.system command
Perl	system(command) or $output = `command`	exec(path, args)
Ruby	system(command) or output = `command`	exec(path, args)
PHP	system(command) or output = `command`	exec(command)
Python	os.system(command) or subprocess.Popen(command)	os.execv(path, args)
S-Lang	system(command)
Windows PowerShell	[Diagnostics.Process]::Start(command)	«Invoke-Item »program arg1 arg2 …

[edit] References