Comparison of programming languages (basic instructions)

Data types

How to declare variable x as the following types:

Integer

	Signed integer	Unsigned integer	Long integer
C	int x;	unsigned int x;	long x:
C++ (STL)		unsigned int x; //OR uint x; //requires STL
C#		uint x;
Java
Pascal	var x: integer;	var x: word;	var x: longint;
Visual Basic	Dim x As Integer		Dim x As Long
Visual Basic .NET		Dim x As UInteger
Python	x = value
JavaScript	var x = value; or var x = new Number (value);
S-Lang	x = value;
FORTRAN 77	INTEGER X

Floating point

	Single precision	Double precision
C	float x;	double x;
C++ (STL)
C#
Java
Pascal	var x: real;	var x: extended;
Visual Basic	Dim x As Single	Dim x As Double
Visual Basic .NET
Python		x = value
JavaScript	var x = value; or var x = new Number (value);
S-Lang	x = valuef;	x = value;
FORTRAN 77	REAL X	DOUBLE PRECISION X

Complex numbers

	Integer	Floating point
C
C++ (STL)	complex<int> x;	complex<float> x; or complex<double> x;
C#
Java
Pascal
Visual Basic
Visual Basic .NET
Python		x = re + imj or x = complex(re, im)
S-Lang		x = re + imi; or x = re + imj;
FORTRAN 77		COMPLEX X

Other

	Text		Boolean
	Character	String
C	char x;	char x[length]; or char *x;	bool x;
C++ (STL)		string x;
C#
Java		String x;	boolean x;
Pascal	var x: char;	var x: string;	var x: boolean;
Visual Basic	Dim x As Char	Dim x As String	Dim x As Boolean
Visual Basic .NET
Python	x = value	x = "string"	x = value
JavaScript	var x = value	var x = "string"; or var x = new String("value");	var x = value; or var x = new Boolean (value);
S-Lang	x = value;	x = "string";	x = value;
FORTRAN 77	CHARACTER*1 X	CHARACTER*length X	LOGICAL X

Array types

How to declare x as an array whose components do not have any particular defined values:

	one-dimensional array	multi-dimensional array
C	type x[n];	type x[n1][n2]...;
C++ (STL)	vector<type> x(n);
C#	type[] x = new type[n];	type[,,...] x = new type[n1,n2,...];
Java		type[][]... x = new type[n1][n2]...;
JavaScript	var x = new Array (); or var x = [];	var x = new Array (new Array (), new Array (), ...); or var x = [[], [], [], ...];
Pascal	var x: array[0...n] of type;	var x: array[0...n1, 0...n2] of type;
Visual Basic	Dim x(n) As type	Dim x(n1,n2,...) As type
Visual Basic .NET
Python
S-Lang	x = type[n];	x = type[n1,n2,...];
FORTRAN 77	type X(N)	type X(N1,N2,...)

Control flow

Statements in square brackets are optional

Conditional statements

	if	else if	select case
C	if (condition) { instructions } [else { instructions }]	if (condition) { instructions } else if (condition) { instructions } ... [else { instructions }]	switch (variable) { case case1: instructions break; ... [default: instructions;]}
C++ (STL)
C#
Java
JavaScript
Pascal	if condition then begin \n instructions \n end [\n else begin \n instructions \n end];	if condition then begin \n instructions \n end \n else if condition then begin \n instructions \n end ... [\n else begin \n instructions \n end];	case variable of \n meaning: instructions; \n ... [else: instructions \n] end;
Visual Basic	If condition Then \n instructions \n [Else instructions \n] End If	If condition Then \n instructions \n ElseIf condition Then \n instructions \n ... [Else instructions \n] End If	Select Case variable \n Case case1 \n instructions \n ... [Case Else \n instructions \n] End Select
Visual Basic .NET
Python	if condition : \n \t instructions \n [else: \n \t instructions \n]	if condition : \n \t instructions \n elif: \n \t instructions \n ... [else: \n \t instructions \n]
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 \n instructions \n [ELSE \n instructions \n] ENDIF	IF (condition) THEN \n instructions \n ELSEIF (condition) THEN \n instructions \n ... [ELSE \n instructions \n] ENDIF

Loop statements

	while	do while	for i = 1 to N	foreach
C	while (condition) { instructions }	do { instructions } while (condition)	for ([type] i = 0; i<N; i++) { instructions }
C++ (STL)
C#				foreach (type item in set) { instructions }
Java				for (type item : set) { instructions }
JavaScript			for (i = 0; i<N; i++) { instructions }	for (property in object) { object [property] }
Pascal	while condition do begin \n instructions \n end	repeat \n instructions \n until condition;	for i := 1 [step 1] to N do begin \n instructions \n end;
Visual Basic	Do While condition \n instructions \n Loop	Do \n instructions \n Loop While condition	For i = 1 To N [Step 1] \n instructions \n Next i
Visual Basic .NET			For i[ As type] = 1 To N [Step 1] \n instructions \n Next i	For Each item As type In set \n instructions \n Next item
Python	while condition : \n \t instructions \n [else: \n \t instructions \n]		for i in range(0, N): \n \t instructions \n [else: \n \t instructions \n]	for item in set: \n \t instructions \n [else: \n \t instructions \n]
S-Lang	while (condition) { instructions } [then optional-block]	do { instructions } while (condition) [then optional-block]	for (i = 0; i<N; i++) { instructions } [then optional-block]	foreach item (set) [using (what)] { instructions } [then optional-block]
FORTRAN 77			DO nnnn I = 1,N \n instructions \n nnnn CONTINUE

Exceptions

Further information: Exception handling syntax

	raise	handler
C
C++ (STL)	throw exception;	try { instructions } catch [(exception)] { instructions } ...
C#		try { instructions } catch [(exception)] { instructions } ... [finally { instructions }]
Java
JavaScript		try { instructions } catch (exception) { instructions } [finally { instructions }]
Pascal
Visual Basic
Visual Basic .NET	Throw exception	Try \n instructions \n Catch [exception] [When condition] \n instructions \n ... [Finally \n instructions \n] End Try
Python	raise exception	try: \n \t instructions \n except[ exception]: \n \t instructions \n ... [else \n \t instructions \n] [finally: \n \t instructions \n]
S-Lang	throw exception;	try { instructions } catch [exception] ... [finally { instructions }]
FORTRAN 77

Function declaration

Statements in square brackets are optional

	basic	value-returning function	main function
C	void foo([parameters]) { instructions }	type foo([parameters]) { instructions }	int main([void]) { } or int main(int argc, char *argv[]) { instructions }
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 }
Pascal	procedure foo([parameters]) \n begin instructions end;	function foo([parameters]):type \n begin instructions end;
Visual Basic	Sub Foo([parameters]) \n instructions \n End Sub	Function Foo([parameters]) As type \n instructions \n End Function
Visual Basic .NET			Sub Main([ByVal CmdArgs() As String]) \n instructions \n End Sub or Function Main([ByVal CmdArgs() As String]) As Integer \n instructions \n End Function
Python	def foo([parameters]): \n \t instructions \n	def foo([parameters]): \n \t instructions \n return value \n	if __name__ == '__main__': \n \t instructions \n
S-Lang	define foo ([parameters ; qualifiers]) { instructions }	define foo ([parameters ; qualifiers]) { instructions ... return value; }	public define slsh_main () { instructions }
FORTRAN 77	SUBROUTINE FOO[(parameters)] \n instructions \n END	type FUNCTION FOO[(parameters)] \n instructions \n FOO = value \n END	PROGRAM main

Type conversions

	string to integer	string to long integer	string to floating point	integer to string	floating point to string
C	integer = atoi(string);	long = atol(string)	float = atof(string);	sprintf(string, "%i", integer);	sprintf(string, "%f", float);
C++ (STL)	stringstream(string) >> integer;	stringstream(string) >> long;	stringstream(string) >> float;	stringstream(string) << integer;	stringstream(string) << float;
C#	integer = int.Parse(string);	long = long.Parse(string);	float = float.Parse(string); or double = double.Parse(string);	string = integer.ToString();	string = float.ToString();
Java	integer = Integer.parseInt(string);	long = Long.parseLong(string);	float = Float.parseFloat(string); or double = Double.parseDouble(string);	string = integer;	string = float;
JavaScript	integer = parseInt (string); or integer = new Number (string) or integer = string*1;	long = new Number (string) or long = string*1;	float = parseFloat(string); or float = new Number (string) or float = string*1;	string = integer.toString (); or string = new String (integer); or string = integer+"";	string = float.toString (); or string = new String (float); or string = float+"";
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(integer)	string = CStr(float)
Visual Basic .NET
Python	integer = int(string)		float = float(string)	string = str(integer)	string = str(float)
S-Lang	integer = atoi(string);	long = atol(string);	float = atof(string);	string = string(integer);	string = string(float);
FORTRAN 77	READ(string,format) integer		READ(string,format) float	WRITE(string,format) integer	WRITE(string,format) float

Standard Input and Standard Output

	read from	write to
	stdin	stdout	stderr
C	scanf( format, &x ); or fscanf(stdin, format, &x );	printf( format, x ); or fprintf(stdout, format, x );	fprintf(stderr, format, x );
C++	cin >> x;	cout << x;	cerr << x; clog << x;
C#	x = Console.Read(); or x = Console.ReadLine();	Console.Write(x); or Console.WriteLine(x);	Console.Error.Write(x); or Console.Error.WriteLine(x);
Java	x = System.in.read();	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);
Pascal	read(x); or readln(x);	write(x); or writeln(x);
Visual Basic	Input x	Print x or  ? x
Visual Basic .NET	x = Console.Read() or x = Console.ReadLine()	Console.Write(x) or Console.WriteLine(x)	Console.Error.Write(x) or Console.Error.WriteLine(x)
Python	For numbers: x = input() For strings: x = raw_input()	print x or sys.stdout.write(x)	sys.stderr.write(x)
S-Lang	fgets (&x, stdin)	fputs (x, stdout)	fputs (x, stderr)
FORTRAN 77	READ(5,format) variable names	WRITE(6,format) expressions

Reading command-line arguments

	Argument values	Argument counts
C	argv[n]	argc
C++
C#	args[n]	args.Length
Java		args.length
Pascal	ParamStr(n)	ParamCount
Visual Basic
Visual Basic .NET	CmdArgs(n)	CmdArgs.Length
Python	sys.argv	len(sys.argv)
S-Lang	__argv	__argc
FORTRAN 77