Comparison of programming languages (basic instructions)

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

Conventions of this article[edit]

The bold is the literal code. The non-bold is interpreted by the reader. Statements in guillemets (« … ») are optional. Tab indicates a necessary indent (with whitespace).

Type identifiers[edit]

Integers[edit]

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
Ada[1] range -2**7 .. 2**7 - 1[j] range 0 .. 2**8 - 1[j] or mod 2**8[k] range -2**15 .. 2**15 - 1[j] range 0 .. 2**16 - 1[j] or mod 2**16[k] range -2**31 .. 2**31 - 1[j] range 0 .. 2**32 - 1[j] or mod 2**32[k] range -2**63 .. 2**63 - 1[j] mod 2**64[k] Integer[j] range 0 .. 2**Integer'Size - 1[j] or mod Integer'Size[k] N/A
ALGOL 68 (variable-width) short short int[c] N/A short int[c] N/A int[c] N/A long int[c] N/A int[c] N/A long long int [a][g]
bytes & bits
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++ (C++11 fixed-width)
C (C99 variable-width) signed char unsigned char short[c] unsigned short[c] long[c] unsigned long[c] long long[c] unsigned long long[c]
C++ (C++11 variable-width)
Objective-C signed char unsigned char short[c] unsigned short[c] long[c] unsigned long[c] long long[c] unsigned long long[c] int
or
NSInteger
unsigned int
or
NSUInteger
C# sbyte byte short ushort int uint long ulong IntPtr UIntPtr System.Numerics.BigInteger
(.NET 4.0)
Java byte N/A char[b] N/A N/A N/A N/A java.math.BigInteger
Go int8 uint8 or byte int16 uint16 int32 uint32 int64 uint64 int uint big.Int
Swift Int8 UInt8 Int16 UInt16 Int32 UInt32 Int64 UInt64 Int UInt
D byte ubyte short ushort int uint long ulong N/A N/A BigInt
Common Lisp[2] bignum
Scheme
ISLISP[3] bignum
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 System.Numerics.BigInteger
(.NET 4.0)
Python 2.x N/A N/A N/A N/A int N/A long
Python 3.x N/A N/A N/A N/A N/A int
S-Lang N/A N/A N/A N/A N/A N/A
Fortran INTEGER(KIND = n)[f] N/A INTEGER(KIND = n)[f] N/A INTEGER(KIND = n)[f] N/A INTEGER(KIND = n)[f] N/A
PHP N/A N/A int [m] N/A int [m] N/A N/A [e]
Perl 5 N/A[d] N/A[d] N/A[d] N/A[d] N/A[d] Math::BigInt
Perl 6 int8 uint8 int16 uint16 int32 uint32 int64 uint64 Int N/A
Ruby N/A N/A N/A N/A Fixnum N/A Bignum
Erlang[n] N/A N/A N/A N/A integer() N/A integer()[o]
Scala Byte N/A Short Char[l] Int N/A Long N/A N/A N/A scala.math.BigInt
Seed7 N/A N/A N/A N/A N/A N/A integer N/A N/A N/A bigInteger
Smalltalk N/A N/A N/A N/A SmallInteger[i] N/A LargeInteger[i]
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
Eiffel INTEGER_8 NATURAL_8 INTEGER_16 NATURAL_16 INTEGER_32 NATURAL_32 INTEGER_64 NATURAL_64 INTEGER NATURAL N/A
COBOL[h] BINARY-CHAR «SIGNED» BINARY-CHAR UNSIGNED BINARY-SHORT «SIGNED» BINARY-SHORT UNSIGNED BINARY-LONG «SIGNED» BINARY-LONG UNSIGNED BINARY-DOUBLE «SIGNED» BINARY-DOUBLE UNSIGNED N/A N/A N/A
Mathematica N/A N/A N/A N/A N/A Integer

^a The standard constants int shorts and int lengths can be used to determine how many 'short's and 'long's 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.
^b Commonly used for characters.
^c 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[citation needed] also define the [u]intN_t exact-width types in the stdint.h header. SeeC syntax#Integral types for more information.
^d Perl 5 does not have distinct types. Integers, floating point numbers, strings, etc. are all considered "scalars".
^e PHP has two arbitrary-precision libraries. The BCMath library just uses strings as datatype. The GMP library uses an internal "resource" type.
^f The value of "n" is provided by the SELECTED_INT_KIND[4] intrinsic function.
^g ALGOL 68G's run time option --precision "number" can set precision for long long ints 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.
^h COBOL allows the specification of a required precision and will automatically select an available type capable of representing the specified precision. "PIC S9999", for example, would required a signed variable of four decimal digits precision. If specified as a binary field, this would select a 16 bit signed type on most platforms.
^i Smalltalk automatically chooses an appropriate representation for integral numbers. Typically, two representations are present, one for integers fitting the native word size minus any tag bit (SmallInteger) and one supporting arbitrary sized integers (LargeInteger). Arithmetic operations support polymorphic arguments and return the result in the most appropriate compact representation.
^j Ada range types are checked for boundary violations at run-time (as well as at compile-time for static expressions). Run time boundary violations raise a "constraint error" exception. Ranges are not restricted to powers of two. Commonly predefined Integer subtypes are: Positive (range 1 .. Integer'Last) and Natural (range 0 .. Integer'Last). Short_Short_Integer (8 bit), Short_Integer (16 bit) and Long_Integer (64 bit) are also commonly predefined, but not required by the Ada standard. Run time checks can be disabled if performance is more important than integrity checks.
^k Ada modulo types implement modulo arithmetic in all operations, i.e. no range violations are possible. Modulos are not restricted to powers of two.
^l Commonly used for characters like Java's char.
^m int in PHP has the same width as long type in C has on that system [c].
^n Erlang is dynamically typed. The type identifiers are usually used to specify types of record fields and the argument and return types of functions.[5]
^o When it exceeds 1 word.

Floating point[edit]

Single precision Double precision Processor dependent
Ada[1] Float Long_Float N/A
ALGOL 68 real[a] long real[a] short real, long long real, etc.[d]
C float[b] double long double[f]
Objective-C
C++ (STL)
C# float N/A
Java
Go float32 float64
Swift Float Double
D float double real
Common Lisp
Scheme
ISLISP
Pascal (Free Pascal) single double real
Visual Basic Single Double N/A
Visual Basic .NET
Xojo
Python N/A float
JavaScript Number[6] N/A
S-Lang
Fortran REAL(KIND = n)[c]
PHP float
Perl
Perl 6 num32 num64 Num
Ruby N/A Float N/A
Scala Float Double
Seed7 N/A float
Smalltalk Float Double
Windows PowerShell
OCaml N/A float N/A
F# float32
Standard ML N/A real
Haskell (GHC) Float Double
Eiffel REAL_32 REAL_64
COBOL FLOAT-BINARY-7[e] FLOAT-BINARY-34[e] FLOAT-SHORT, FLOAT-LONG, FLOAT-EXTENDED
Mathematica N/A N/A Real

^a The standard constants real shorts and real lengths can be used to determine how many 'short's and 'long's 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.
^b declarations of single precision often are not honored
^c The value of "n" is provided by the SELECTED_REAL_KIND[7] intrinsic function.
^d ALGOL 68G'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.
^e These IEEE floating-point types will be introduced in the next COBOL standard.
^f Same size as 'double' on many implementations.

Complex numbers[edit]

Integer Single precision Double precision Half and Quadruple precision etc.
Ada[1] N/A Complex[b] Complex[b] Complex[b]
ALGOL 68 N/A compl long compl etc. short compl etc. & long long compl etc.
C (C99) [8] N/A float complex double complex N/A
C++ (STL) N/A std::complex<float> std::complex<double>
C# N/A N/A System.Numerics.Complex
(.Net 4.0)
Java N/A N/A N/A
Go N/A complex64 complex128
D N/A cfloat cdouble
Objective-C N/A 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 System.Numerics.Complex
(.Net 4.0)
Perl Math::Complex
Perl 6 complex64 complex128 Complex
Python complex N/A
JavaScript N/A N/A
S-Lang N/A N/A
Fortran COMPLEX(KIND = n)[a]
Ruby Complex N/A Complex
Scala N/A N/A N/A
Seed7 N/A N/A complex
Smalltalk Complex Complex Complex
Windows PowerShell N/A N/A
OCaml N/A N/A Complex.t
F# System.Numerics.Complex
(.Net 4.0)
Standard ML N/A N/A N/A
Haskell (GHC) N/A Complex.Complex Float Complex.Complex Double
Eiffel N/A N/A N/A
COBOL N/A N/A N/A
Mathematica Complex N/A N/A Complex

^a The value of "n" is provided by the SELECTED_REAL_KIND[7] intrinsic function.

^b Generic type which can be instantiated with any base floating point type.

Other variable types[edit]

Text Boolean Enumeration Object/Universal
Character String[a]
Ada[1] Character String & Bounded_String & Unbounded_String Boolean (item1, item2, ...) tagged null record
ALGOL 68 char string & bytes bool & bits N/A - User defined N/A
C (C99) char
wchar_t
N/A bool[b] enum «name» {item1, item2, ... }; void *
C++ (STL) «std::»string
Objective-C unichar NSString * BOOL id
C# char string bool enum name {item1, item2, ... } object
Java String boolean Object
Go rune string bool const (
item1 = iota
item2
...
)
interface{}
Swift Character String Bool enum name { case item1, item2, ... } Any
D char string bool enum name {item1, item2, ... } std.variant.Variant
Common Lisp
Scheme
ISLISP
Pascal (ISO) char N/A boolean (item1, item2, ...) N/A
Object Pascal (Delphi) string variant
Visual Basic N/A String Boolean Enum name
item1
item2
...
End Enum
Variant
Visual Basic .NET Char Object
Xojo N/A Object or Variant
Python N/A[d] str bool object
JavaScript N/A[d] String Boolean Object
S-Lang
Fortran CHARACTER(LEN = *) CHARACTER(LEN = :), allocatable LOGICAL(KIND = n)[f] CLASS(*)
PHP N/A[d] string bool object
Perl N/A[d]
Perl 6 Char Str Bool enum name <item1 item2 ...> or
enum name <<:item1(value) :item2(value) ...>>
Mu
Ruby N/A[d] String Object[c] Object
Scala Char String Boolean object name extends Enumeration {
val item1, item2, ... = Value
}
Any
Seed7 char string boolean const type: name is new enum
item1,
item2,
...
end enum;
Windows PowerShell
OCaml char string bool N/A[e] N/A
F# type name = item1 = value | item2 = value | ... obj
Standard ML N/A[e] N/A
Haskell (GHC) Char String Bool N/A[e] N/A
Eiffel CHARACTER STRING BOOLEAN N/A ANY
COBOL PIC X PIC X(string length) or PIC X«X...» PIC 1«(number of digitsor PIC 1«1...» N/A OBJECT REFERENCE
Mathematica N/A[d] String 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 evaluate 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.
^e Enumerations in this language are algebraic types with only nullary constructors
^f The value of "n" is provided by the SELECTED_INT_KIND[4] intrinsic function.

Derived types[edit]

Array[edit]

fixed size array dynamic size array
one-dimensional array multi-dimensional array one-dimensional array multi-dimensional array
Ada[1] array (<first> .. <last>) of <type>
or
array (<discrete_type>) of <type>
array (<first1> .. <last1>, <first2> .. <last2>, ...) of <type>
or
array (<discrete_type1>, <discrete_type2>, ...) of <type>
array (<discrete_type> range <>) of <type> array (<discrete_type1> range <>, <discrete_type2> range <>, ...) of <type>
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) type name[size][a] type name[size1][size2][a] type *name
or within a block:
int n = ...; type name[n]
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[][b] type[][]...[b] ArrayList or ArrayList<type>
D type[size] type[size1][size2] type[]
Go [size]type [size1][size2]...type []type [][]type
Swift [type] or Array<type> [[type]] or Array<Array<type>>
Objective-C NSArray NSMutableArray
JavaScript N/A N/A Array[d]
Common Lisp
Scheme
ISLISP
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]

N/A N/A
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
Scala Array[type] Array[...[Array[type]]...] ArrayBuffer[type]
Seed7 array type
or
array [idxType] type
array array type
or
array [idxType] array [idxType] type
array type
or
array [idxType] type
array array type
or
array [idxType] array [idxType] type
Smalltalk Array OrderedCollection
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)
COBOL level-number type OCCURS size «TIMES». one-dimensional array definition... level-number type OCCURS min-size TO max-size «TIMES» DEPENDING «ON» size.[e] N/A

^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. See C syntax#Arrays for further details of syntax and pointer operations.
^b The C-like "type x[]" works in Java, however "type[] x" is the preferred form of array declaration.
^c Subranges are used to define the bounds of the array.
^d JavaScript's array are a special kind of object.
^e The DEPENDING ON clause in COBOL does not create a 'true' variable length array and will always allocate the maximum size of the array.

Other types[edit]

Simple composite types Algebraic data types Unions
Records Tuple expression
Ada[1] type identifier is «abstract» «tagged» «limited» [record
fieldname1 : type;
fieldname2 : type;
...

end record | null record]

N/A Any combination of records, unions and enumerations (as well as references to those, enabling recursive types). type identifier (variation : discrete_type) is record
case variation is
when choice_list1 =>
fieldname1 : type;
...
when choice_list2 =>
fieldname2 : type;
...
...
end case;
end record
ALGOL 68 struct (modename «fieldname», ...); Required types and operators can be user defined union (modename, ...);
C (C99) struct «name» {type name;...}; N/A N/A union {type name;...};
Objective-C
C++ struct «name» {type name;...};[b] «std::»tuple<type1..typen>
C# struct name {type name;...} N/A
Java N/A[a]
JavaScript N/A
D struct name {type name;...} std.variant.Algebraic!(type,...) union {type name;...}
Go struct {
«name» type
...
}
Swift struct name {
var name «: type»
...
}
(«name1:» val1, «name2:» val2, «name3:» val3, ... ) enum name { case Foo«(types)» case Bar «(types)» ... }
Common Lisp (cons val1 val2)[c]
Scheme N/A
ISLISP
Pascal record
name: type;
...
end
N/A N/A record
case type of
value: (types);
...
end
Visual Basic
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 TYPE name
type :: name
...
END TYPE
PHP N/A[a]
Perl N/A[d] N/A
Perl 6 N/A[a]
Ruby OpenStruct.new({:name => value})
Scala case class name(«var» name: type, ...) (val1, val2, val3, ... ) abstract class name

case class Foo(«parameters») extends name
case class Bar(«parameters») extends name
...
or
abstract class name
case object Foo extends name
case object Bar extends name
...
or combination of case classes and case objects

Windows PowerShell
OCaml type name = {«mutable» name : type;...} «(»val1, val2, val3, ... «)» type name = Foo «of type» | Bar «of type» | ... N/A
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» | ...
COBOL level-number name type clauses.

  level-number+n name type clauses.
  ...

N/A N/A name REDEFINES variable type.

^a Only classes are supported.
^b structs in C++ are actually classes, but have default public visibility and are also POD objects. C++11 extended this further, to make classes act identically to POD objects in many more cases.
^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

Variable and constant declarations[edit]

variable constant type synonym
Ada[1] identifier : type «:= initial_value»[e] identifier : constant type := final_value subtype identifier is type
ALGOL 68 modename name «:= initial_value»; modename name = value; mode synonym = modename;
C (C99) type name «= initial_value»; enum{ name = value }; typedef 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; N/A
JavaScript var name «= initial_value»; const name = value;
Go var name type «= initial_value» or
name := initial_value
const name «type» = value type synonym type
Swift var name «: type» «= initial_value» let name «: type» = value typealias 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)
ISLISP (defglobal name initial_value) or
(defdynamic name initial_value)
(defconstant name value) N/A
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
Xojo Dim name As type«= initial_value» N/A
Python name = initial_value N/A synonym = type[b]
CoffeeScript N/A
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+)
N/A
Perl «my» $name «= initial_value»;[c] use constant name => value;
Perl 6 «my «type»» $name «= initial_value»;[c] «my «type»» constant name = value; ::synonym ::= type
Ruby name = initial_value Name = value synonym = type[b]
Scala var name«: type» = initial_value val name«: type» = value type synonym = type
Windows PowerShell «[type]» $name = initial_value N/A N/A
Bash shell name=initial_value N/A N/A
OCaml let name «: type ref» = ref value[d] let name «: type» = value type synonym = type
F# let mutable name «: type» = value
Standard ML val name «: type ref» = ref value[d] 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
COBOL level-number name type clauses. «0»1 name CONSTANT «AS» value. level-number name type clauses «IS» TYPEDEF.
Mathematica name=initialvalue N/A N/A

^a Pascal has declaration blocks. See Comparison of programming languages (basic instructions)#Functions.
^b Types are just regular objects, so you can just assign them.
^c In Perl, the "my" keyword scopes the variable into the block.
^d 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.
^[e] If no initial value is given, an invalid value is automatically assigned (which will trigger a run-time exception if it used before a valid value has been assigned). While this behaviour can be suppressed it is recommended in the interest of predictability. If no invalid value can be found for a type (for example in case of an unconstraint integer type), a valid, yet predictable value is chosen instead.

Control flow[edit]

Conditional statements[edit]

if else if select case conditional expression
Ada[1] if condition then
statements
«else
statements»
end if
if condition1 then
statements
elsif condition2 then
statements
...
«else
statements»
end if
case expression is
when value_list1 => statements
when value_list2 => statements
...
«when others => statements»
end case
(if condition1 then
expression1
«elsif condition2 then
expression2»
...
else
expressionn
)
(case expression is
when value_list1 => expression1
when value_list2 => expression2
...
«when others => expressionn»
)
Seed7 case expression of
when set1 : statements
...
«otherwise: statements»
end case
Modula-2 if condition then
statements
«else
statements»
end
if condition1 then
statements
elsif condition2 then
statements
...
«else
statements»
end
case expression of
caseLabelList : statements |
...
«else statements»
end
ALGOL 68 & "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 )
( condition | statements «| statements» ) ( condition | statements |: condition |  statements ) ( variable | 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 ? 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»
}
Swift if condition {instructions}
«else {instructions}»
if condition {instructions}
else if
condition {instructions}
...
«else {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»
if condition
instructions
elsif condition
instructions
...
«else
instructions»
end
case variable
when case1
instructions
...
«else
instructions»
end
condition ? valueIfTrue : valueIfFalse
Scala if (condition) {instructions}
«else {instructions}»
if (condition) {instructions}
else if (
condition) {instructions}
...
«else {instructions}»
expression match {
case pattern1 => expression
case pattern2 => expression
...
«case _ => expression»
}[b]
if (condition) valueIfTrue else valueIfFalse
Smalltalk condition ifTrue:
trueBlock
«ifFalse:
falseBlock»
end
condition ifTrue: trueBlock ifFalse: falseBlock
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)»)
ISLISP (if condition
(progn instructions)
«(progn instructions)»)
(cond (condition1 instructions)
(condition2 instructions)
...
«(t instructions)»)
(case expression
(case1 instructions)
(case2 instructions)
...
«(t instructions)»)
(if condition valueIfTrue valueIfFalse)
Pascal if condition then begin
instructions
end
«else begin
instructions
end»[c]
if condition then begin
instructions
end
else if
condition then begin
instructions
end
...
«else begin
instructions
end»[c]
case variable of
case1: instructions
...
«else: instructions»
end[c]
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)
Xojo
Python [a] if condition :
Tab instructions
«else:
Tab instructions»
if condition :
Tab instructions
elif condition :
Tab instructions
...
«else:
Tab 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»[b]
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»[b]
Haskell (GHC) if condition then expression else expression
or
when condition (do instructions)
or
unless notcondition (do instructions)
result | condition = expression
| condition = expression
| otherwise = expression
case value of {
pattern1 -> expression;
pattern2 ->expression;
...
«_ -> expression»
}[b]
Bash shell

if condition-command; then
    expression
«else
    expression»
fi

if condition-command; then
    expression
elif condition-command; then
    expression
«else
    expression»
fi

case "$variable" in
"$condition1" )
    command...


"$condition2" )
    command...


esac

CoffeeScript if condition then expression «else expression» if condition then expression else if condition then expression «else expression» switch expression
when condition then expression
else expression
All conditions are expressions
if condition
expression
«else
expression»
if condition
expression
else if condition
expression
«else
expression»
expression if condition unless condition
expression
else unless condition
expression
«else
expression»
switch expression
when condition
expression
«else
expression»
unless condition
expression
«else
expression»
expression unless condition
COBOL IF condition «THEN»
expression
«ELSE
expression».
[d]
EVALUATE expression «ALSO expression...»
WHEN case-or-condition «ALSO case-or-condition...»
expression
...
«WHEN OTHER
expression»
END-EVALUATE
if else if select case conditional expression

^a 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 is required). The conditional expression syntax does not follow this rule.
^b This is pattern matching and is similar to select case but not the same. It is usually used to deconstruct algebraic data types.
^c In languages of the Pascal family, the semicolon is not part of the statement. It is a separator between statements, not a terminator.
^d END-IF may be used instead of the period at the end.

Loop statements[edit]

while do while for i = first to last foreach
Ada[1] while condition loop
statements
end loop
loop
statements
exit when not condition
end loop
for index in «reverse» [first .. last | discrete_type] loop
statements
end loop
for item of «reverse» iterator loop
statements
end loop

(for [all | some] [in | of] [first .. last | discrete_type | iterator] => predicate)[b]
ALGOL 68 «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 } N/A
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+, deprecated[9])
or
for (var item of set) { instructions } (EcmaScript 6 proposal, supported in Firefox[10])
PHP foreach (range(first, last) 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; $i++) { instructions } foreach (item in set) { instructions using item }
D foreach (i; first ... last) { instructions } foreach («type» item; set) { instructions }
Go for condition { instructions } for i := first; i <= last; i++ { instructions } for key, item := range set { instructions }
Swift while condition { instructions } do { instructions } while condition for i = first ... last { instructions } or
for i = first ..< last+1 { instructions } or
for var i = first; i <= last; i++ { instructions }
for item in set { instructions }
Perl while (condition) { instructions } or
until (notcondition) { instructions }
do { instructions } while (condition) or
do { instructions } until (notcondition)
for«each» «$i» (first .. last) { 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
for i in first...last+1
instructions
end
or
first.upto(last) { |i| instructions }
for item in set
instructions
end
or
set.each { |item| instructions }
Bash shell while condition ;do
instructions
done
or
until notcondition ;do
instructions
done
N/A for ((i = first; i <= last; ++i)) ; do
instructions

done

for item in set ;do
instructions
done
Scala while (condition) { instructions } do { instructions } while (condition) for (i <- first to last «by 1») { instructions }
or
first to last «by 1» foreach (i => { instructions })
for (item <- set) { instructions }
or
set foreach (item => { instructions })
Smalltalk conditionBlock whileTrue:
loopBlock
loopBlock doWhile:
conditionBlock
first to: last do:
loopBlock
collection do:
loopBlock
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)
ISLISP (while condition instructions) (tagbody loop instructions (if condition (go loop)) (for ((i first (+ i 1))) ((>= i last)) instructions) (mapc (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]
for item in set do ...
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
Xojo While condition
instructions
Wend
Do Until notcondition
instructions
Loop
or
Do
instructions
Loop Until notcondition
Python while condition :
Tab instructions
«else:
Tab instructions»
N/A for i in range(first, last+1):
Tab instructions
«else:
Tab instructions»
(Python 3.x)

for i in xrange(first, last+1):
Tab instructions
«else:
Tab instructions»
(Python 2.x)

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 DO WHILE (condition)
instructions
ENDDO
DO
instructions
IF (
condition) EXIT
ENDDO
DO I = first,last
instructions
ENDDO
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 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 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_ [first..last] (\i -> do instructions) Control.Monad.forM_ list (\item -> do instructions)
Eiffel from
setup
until
condition
loop
instructions
end
CoffeeScript while condition
expression
N/A for i in [first..last]
expression
for item in set
expression
expression while condition
while condition then expression
until condition
expression
expression until condition for i in [first..last] then expression for item in set then expression
until condition then expression expression for i in [first..last] expression for item in set
COBOL PERFORM procedure-1 «THROUGH procedure-2» ««WITH» TEST BEFORE» UNTIL condition[c] PERFORM procedure-1 «THROUGH procedure-2» «WITH» TEST AFTER UNTIL condition[c] PERFORM procedure-1 «THROUGH procedure-2» VARYING i FROM first BY increment UNTIL i > last[d] N/A
PERFORM ««WITH» TEST BEFORE» UNTIL condition
expression
END-PERFORM
PERFORM «WITH» TEST AFTER UNTIL condition
expression
END-PERFORM
PERFORM VARYING i FROM first BY increment UNTIL i > last
expression
END-PERFORM[d]

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

^b This implements the universal quantifier ("for all" or "∀") as well as the existential quantifier ("there exists" or "∃").

^c THRU may be used instead of THROUGH.

^d «IS» GREATER «THAN» may be used instead of >.

Exceptions[edit]

Further information: Exception handling syntax
throw handler assertion
Ada[1] raise exception_name «with string_expression» begin
statements
exception
when exception_list1 => statements;
when exception_list2 => statements;
...
«when others => statements;»
end[b]
pragma Assert («Check =>» boolean_expression ««Message =>» string_expression»)

[function | procedure | entry] with
Pre => boolean_expression
Post => boolean_expression

any_type with Type_Invariant => boolean_expression
C (C99) longjmp(state, exception); switch (setjmp(state)) { case 0: instructions break; case exception: instructions ... } assert(condition);
C++ 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 } «finally { 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);
Swift N/A N/A assert(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
Smalltalk exception raise instructionBlock on: exception do: handlerBlock assert: conditionBlock
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»))
...)[a]
(assert condition) or
(assert condition
«(place)
«error»»)
or
(check-type var type)
Scheme (R6RS) (raise exception) (guard (con (condition instructions) ...) instructions) ?
ISLISP (error "error-string" objects) or
(signal-condition condition continuable)
(with-handler
handler form*)
?
Pascal raise Exception.Create() try Except on E: exception do begin instructions end; end; ?
Visual Basic Err.Raise ERRORNUMBER With New Try: On Error Resume Next
OneInstruction
.Catch: On Error GoTo 0: Select Case .Number
Case ERRORNUMBER
instructions
End Select: End With
'*** Try class ***
Private mstrDescription As String
Private mlngNumber As Long
Public Sub Catch()

mstrDescription = Err.Description

mlngNumber = Err.Number

End Sub
Public Property Get Number() As Long

Number = mlngNumber

End Property
Public Property Get Description() As String

Description = mstrDescription
End Property
[11]
Debug.Assert condition
Visual Basic .NET Throw exception Try
instructions
Catch «exception» «When condition»
instructions
...
«Finally
instructions»
End Try
Debug.Assert(condition)
Xojo Raise exception Try
instructions
Catch «exception»
instructions
...
«Finally
instructions»
End Try
N/A
Python raise exception try:
Tab instructions
except «exception»:
Tab instructions
...
«else:
Tab instructions»
«finally:
Tab instructions»
assert condition
Fortran 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
COBOL RAISE «EXCEPTION» exception USE «AFTER» EXCEPTION OBJECT class-name. or

USE «AFTER» EO class-name. or
USE «AFTER» EXCEPTION CONDITION exception-name «FILE file-name». or
USE «AFTER» EC exception-name «FILE file-name».

N/A

^a 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.

^b Uncaught exceptions are propagated to the innermost dynamically enclosing execution. Exceptions are not propagated across tasks (unless these tasks are currently synchronised in a rendezvous).

Other control flow statements[edit]

exit block(break) continue label branch (goto) return value from generator
Ada[1] exit «loop_name» «when condition» N/A label: goto label N/A
ALGOL 68 value exit; ... do statements; skip exit; label: statements od label: ... go to label; ...

goto label; ...
label; ...

yield(value)

(Callback)[12]

C (C99) break; continue; label: goto label; N/A
Objective-C
C++ (STL)
D
C# yield return value;
Java break «label»; continue «label»; N/A
JavaScript yield value«;»
PHP break «levels»; continue «levels»; goto label; yield «key =>» value;
Perl last «label»; next «label»;
Perl 6
Go break «label» continue «label» goto label
Swift break «label» continue «label» N/A
Bash shell break «levels» continue «levels» N/A N/A N/A
Common Lisp (return) or
(return-from block) or
(loop-finish)
(tagbody tag
...
tag
...)
(go tag)
Scheme
ISLISP (return-from block) (tagbody tag
...
tag
...)
(go tag)
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
Xojo
Python break continue N/A yield value
RPG IV LEAVE; ITER;
S-Lang break; continue;
Fortran EXIT CYCLE label[b] GOTO label N/A
Ruby break next
Windows PowerShell break «label» continue
OCaml N/A
F#
Standard ML
Haskell (GHC)
COBOL EXIT PERFORM or EXIT PARAGRAPH or EXIT SECTION or EXIT. EXIT PERFORM CYCLE label «SECTION». GO TO label N/A
Ya break «from where»; f.e.

break for switch;

continue «to where»; f.e.

continue for switch;

:label goto :label; N/A

^a Pascal has declaration blocks. See Comparison of programming languages (basic instructions)#Functions.
^b label must be a number between 1 and 99999.

Functions[edit]

See reflection for calling and declaring functions by strings.

calling a function basic/void function value-returning function required main function
Ada[1] foo «(parameters)» procedure foo «(parameters)» is begin statements end foo function foo «(parameters)» return type is begin statements end foo N/A
ALGOL 68 foo«(parameters)»; proc foo = «(parameters)» void: ( instructions ); proc foo = «(parameters)» rettype: ( instructions ...; retvalue ); N/A
C (C99) foo(«parameters») void 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... 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; } N/A
Go func foo(«parameters») { instructions } func foo(«parameters») type { instructions ... return value } func main() { instructions }
Swift func foo(«parameters») { instructions } func foo(«parameters») -> type { instructions ... return value } N/A
Common Lisp (foo «parameters») (defun foo («parameters»)
instructions)
or
(setf (symbol-function 'symbol)
lambda)
(defun foo («parameters»)
...
value)
N/A
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))
ISLISP (defun foo («parameters»)
instructions)
(defun foo («parameters»)
...
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
Xojo
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 foo («arguments»)
CALL sub_foo (
«arguments»)[c]
SUBROUTINE sub_foo («arguments»)
instructions
END SUBROUTINE[c]
type FUNCTION foo («arguments»)
instructions
...
foo
= value
END FUNCTION[c]
PROGRAM main
instructions
END PROGRAM
Forth «parameters» FOO : FOO « stack effect comment: ( before -- ) »
instructions
 ;
: FOO « stack effect comment: ( before -- after ) »
instructions
 ;
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; }
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
Scala def foo«(parameters)»«: Unit =» { instructions } def foo«(parameters)»«: type» = { instructions ... «return» value } def main(args: Array[String]) { instructions }
Windows PowerShell foo «parameters» function foo { instructions };
or
function foo { «param(parameters)» instructions }
function foo «(parameters)» { instructions … return value }; or
function foo { «param(parameters)» instructionsreturn value }
N/A
Bash shell foo «parameters»

function foo {
    instructions
}
or
foo () {
    instructions
}

function foo {
    instructions
    return «exit_code»
}
or
foo () {
    instructions
    return «exit_code»
}

  • parameters
    • $n ($1, $2, $3, ...)
    • $@ (all parameters)
    • $# (the number of parameters)
    • $0 (this function name)
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
Eiffel foo («parameters») foo («parameters»)
require
preconditions
do
instructions
ensure
postconditions
end
foo («parameters»): type
require
preconditions
do
instructions
Result := value
ensure
postconditions
end
[b]
CoffeeScript foo() foo = -> foo = -> value N/A
foo parameters foo = () -> foo = ( parameters ) -> value
COBOL CALL "foo" «USING parameters»
«exception-handling»
«END-CALL»[d]
«IDENTIFICATION DIVISION.»

PROGRAM-ID. foo.
«other divisions...»
PROCEDURE DIVISION «USING parameters».

instructions.
«IDENTIFICATION DIVISION.»

PROGRAM-ID/FUNCTION-ID. foo.
«other divisions...»
DATA DIVISION.
«other sections...»
LINKAGE SECTION.
«parameter definitions...»
variable-to-return definition
«other sections...»
PROCEDURE DIVISION «USING parameters» RETURNING variable-to-return.

instructions.
N/A
«FUNCTION» foo«(«parameters»)» N/A

^a Pascal requires "forward;" for forward declarations.
^b Eiffel allows the specification of an application's root class and feature.
^c In Fortran, function/subroutine parameters are called arguments (since PARAMETER is a language keyword); the CALL keyword is required for subroutines.
^d Instead of using "foo", a string variable may be used instead containing the same value.

Type conversions[edit]

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
Ada[1] Integer'Value (string_expression) Long_Integer'Value (string_expression) Float'Value (string_expression) Integer'Image (integer_expression) Float'Image (float_expression)
ALGOL 68 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));
orv

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); or
string = String.valueOf(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 = Number (string) or
float = +string
string = number.toString (); or
string = new String (number); or
string = String (number); or
string = number+"";
Go integer, error = strconv.Atoi(string) or
integer, error = strconv.ParseInt(string, 10, 0)
long, error = strconv.ParseInt(string, 10, 64) float, error = strconv.ParseFloat(string, 64) string = strconv.Itoa(integer) or
string = strconv.FormatInt(integer, 10) or
string = fmt.Sprint(integer)
string = strconv.FormatFloat(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))
ISLISP (setf integer (convert string <integer>)) (setf float (convert string <float>)) (setf string (convert number <string>))
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
Xojo integer = Val(string) long = Val(string) double = Val(string) or
double = CDbl(string)
string = CStr(number) or
string = Str(number)
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[b] 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
Scala integer = string.toInt long = string.toLong float = string.toFloat or
double = string.toDouble
string = number.toString
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
COBOL MOVE «FUNCTION» NUMVAL(string)[c] TO number MOVE number TO numeric-edited

^a JavaScript only uses floating point numbers so there are some technicalities.[6]
^b Perl doesn't have separate types. Strings and numbers are interchangeable.
^c NUMVAL-C or NUMVAL-F may be used instead of NUMVAL.

Standard stream I/O[edit]

read from write to
stdin stdout stderr
Ada[1] Get (x) Put (x) Put (Standard_Error, x)
ALGOL 68 readf(($format$, x)); or
getf(stand in, ($format$, x));
printf(($format$, x)); or
putf(stand out, ($format$, x));
putf(stand error, ($format$, x));[a]
C (C99) scanf(format, &x); or
fscanf(stdin, format, &x); [b]
printf( format, x); or
fprintf(stdout, format, x); [c]
fprintf(stderr, format, x );[d]
Objective-C data = [[NSFileHandle fileHandleWithStandardInput] readDataToEndOfFile]; [[NSFileHandle fileHandleWithStandardOutput] writeData:data]; [[NSFileHandle fileHandleWithStandardError] writeData:data];
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);
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(format, x); or
System.out.println(x);
System.err.print(x); or
System.err.printf(format, x); or
System.err.println(x);
Go fmt.Scan(&x) or
fmt.Scanf(format, &x) or
x = bufio.NewReader(os.Stdin).ReadString('\n')
fmt.Println(x) or
fmt.Printf(format, x)
fmt.Fprintln(os.Stderr, x) or
fmt.Fprintf(os.Stderr, format, x)
Swift 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)
ISLISP (setf x (read-line)) (format (standard-output) format x) (format (error-output) 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)
Xojo x = StandardInputStream.Read() or
x = StandardInputStreame.ReadLine()
StandardOutputStream.Write(x) or
StandardOutputStream.WriteLine(x)
StdErr.Write(x) or
StdErr.WriteLine(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(, end=""») print(, 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[e]
WRITE(*,format) expressions or
WRITE(OUTPUT_UNIT,
format) expressions[e]
WRITE(ERROR_UNIT,format) expressions[e]
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;
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(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
COBOL ACCEPT x DISPLAY x


^a Algol 68 additionally as the "unformatted" transput routines: read, write, get and put.
^b gets(x) and fgets(x, length, stdin) read unformatted text from stdin. Use of gets is not recommended.
^c puts(x) and fputs(x, stdout) write unformatted text to stdout.
^d fputs(x, stderr) writes unformatted text to stderr
^e INPUT_UNIT, OUTPUT_UNIT, ERROR_UNIT are defined in the ISO_FORTRAN_ENV module.[13]

Reading command-line arguments[edit]

Argument values Argument counts Program name / Script name
Ada[1] Argument (n) Argument_Count Command_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 implementation
WScript.Arguments(n) WScript.Arguments.length WScript.ScriptName or WScript.ScriptFullName
Go os.Args[n] len(os.Args) first argument
Swift Process.arguments[n] or
C_ARGV[n]
Process.arguments.count or
C_ARGC
first argument
Common Lisp ? ? ?
Scheme (R6RS) (list-ref (command-line) n) (length (command-line)) first argument
ISLISP N/A N/A N/A
Pascal ParamStr(n) ParamCount first argument
Visual Basic Command[a] N/A App.Path
Visual Basic .NET CmdArgs(n) CmdArgs.Length [Assembly].GetEntryAssembly().Location
Xojo System.CommandLine (string parsing) Application.ExecutableFile.Name
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
Bash shell $n ($1, $2, $3, ...)
$@ (all arguments)
$# $0
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 length args !! n} do { args <- System.getArgs; return length args} System.getProgName
COBOL [b] N/A
  • ^a The command-line arguments in Visual Basic are not separated. A split function Split(string) is required for separating them.
  • ^b The COBOL standard does not include any way to access command-line arguments but common compiler-extensions for accessing them include defining parameters for the main program or using ACCEPT statements.

Execution of commands[edit]

Shell command Execute program Replace current program with new executed program
Ada[1] Not part of the language standard. Commonly done by compiler provided packages or by interfacing to C or Posix.[14]
C system("command"); execl(path, args); or
execv(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)
Xojo Shell.Execute(command «Parameters») FolderItem.Launch(parameters, activate) N/A
D std.process.system("command"); std.process.execv(path, arglist);
Java Runtime.exec(command); or
new ProcessBuilder(command).start();
JavaScript
Windows Script Host implementation
WScript.CreateObject ("WScript.Shell").Run(command «WindowStyle» «isWaitOnReturn»); WshShell.Exec(command)
Common Lisp (shell command)
Scheme (system command)
ISLISP N/A N/A N/A
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` or
$output = qx(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)[a]
Windows PowerShell [Diagnostics.Process]::Start(command) «Invoke-Item »program arg1 arg2 …
Bash shell output=`command` or

output=$(command)

program arg1 arg2 …

^a Compiler-dependent extension.[15]

References[edit]