Comparison of programming languages (syntax)

This comparison of programming languages (syntax) compares the features of language syntax (format) for over 50 various computer programming languages.


Programming language expressions can be broadly classified in three classes:

prefix notation
infix notation
suffix, postfix, or Reverse Polish notation
math-like notation


Programming language statements typically have conventions for:

A statement separator is used to demarcate boundaries between two separate statements. A statement terminator is used to demarcate the end of an individual statement. Line continuation is a convention in languages where the newline character could potentially be misinterpreted as a statement terminator. In such languages, it allows a single statement to span more than just one line.

Language Statement separator-terminator Secondary separator[1]
ABAP period separated
Ada semicolon terminated
ALGOL semicolon separated
ALGOL 68 semicolon and comma separated[2]
AppleScript newline terminated
AutoHotkey newline terminated
BASIC newline terminated colon separated
Boo newline terminated
C semicolon terminates statements comma separates expressions
C++ semicolon terminates statements comma separates expressions
C# semicolon terminated
COBOL whitespace separated, sometimes period separated, optionally separated with commas and semi-colons.
Cobra newline terminated
CoffeeScript newline terminated
D semicolon terminated
Eiffel newline terminated semicolon
Erlang colon separated, period terminated
Falcon newline separated
Fortran newline terminated semicolon
Forth semicolons terminate word definitions
GFA BASIC newline terminated
Go semicolon separated (inserted by compiler)
Haskell (in do-notation) semicolon separated
Haskell (in do-notation, when braces are omitted) newline separated
Java semicolon terminated
JavaScript semicolon separated (but sometimes implicitly inserted on newlines)
Lua whitespace separated (semicolon optional)
Mathematica semicolon separated
MATLAB newline terminated semicolon or comma[3]
Object Pascal (Delphi) semicolon separated
Objective-C semicolon terminated
OCaml semicolon separated
Pascal semicolon separated
Perl semicolon separated
Perl 6 semicolon separated
PHP semicolon terminated
Prolog period terminated
Python newline terminated semicolon
Ruby newline terminated semicolon
Rust semicolon terminates statements comma separates expressions
Scala newline terminated (semicolon optional) semicolon
Seed7 semicolon separated (semicolon termination is allowed)
Simula semicolon separated
S-Lang semicolon separated
Smalltalk period separated
Standard ML semicolon separated
Swift semicolon separated (inserted by compiler)
Visual Basic newline terminated colon separated
Visual Basic .NET newline terminated colon separated
Wolfram Language semicolon separated
Windows PowerShell newline terminated semicolon separated
Xojo newline terminated
Language Statement separator-terminator Secondary separator[1]

Line continuation

Line continuation is generally done as part of lexical analysis: a newline normally results in a token being added to the token stream, unless line continuation is detected.

Whitespace – Languages that do not need continuations
Ampersand as last character of line
Backslash as last character of line
Backtick as last character of line
Hyphen as last character of line
Underscore as last character of line
Ellipsis (as three periods–not one special character)
Comma delimiter as last character of line
Left bracket delimiter as last character of line
Operator as last object of line
Backslash as first character of continued line
Some form of inline comment serves as line continuation
Character position
[End and Begin] using normal quotes


To import a library is a way to read external, possibly compiled, routines, programs or packages. Imports can be classified by level (module, package, class, procedure,...) and by syntax (directive name, attributes,...)

File import
Package import
Class import
Procedure/function import

The above statements can also be classified by whether they are a syntactic convenience (allowing things to be referred to by a shorter name, but they can still be referred to by some fully qualified name without import), or whether they are actually required to access the code (without which it is impossible to access the code, even with fully qualified names).

Syntactic convenience
Required to access code


A block is a notation for a group of two or more statements, expressions or other units of code that are related in such a way as to comprise a whole.

Braces (a.k.a. curly brackets) { ... }
Parentheses ( ... )
Brackets [ ... ]
begin ... end
do ... done
do ... end
X ... end (e.g. if ... end):
(begin ...)
(progn ...)
(do ...)


Comments can be classified by:

Inline comments

Inline comments are generally those that use a newline character to indicate the end of a comment, and an arbitrary delimiter or sequence of tokens to indicate the beginning of a comment.


Symbol Languages
C Fortran 77 and earlier; the 'C' must be in column 1 of a line to indicate a comment.
REM, ::, : BASIC, COMMAND.COM, cmd.exe, batch files
NB. J; from the (historically) common abbreviation Nota bene, the Latin for "note well".
APL; the mnemonic is the glyph (jot overstruck with shoe-down) resembles a desk lamp, and hence "illuminates" the foregoing.
# Bourne shell and other UNIX shells, Cobra, Perl, Python, Ruby, Seed7, Windows PowerShell, PHP, R, Make, Maple, Nimrod[9]
% TeX, Prolog, MATLAB,[10] Erlang, S-Lang, Visual Prolog
// ActionScript, C (C99), C++, C#, D, Go, Java, JavaScript, Object Pascal (Delphi), Objective-C, PHP, Rust, Scala, SASS, Swift, Xojo
' Monkey, Visual Basic, VBScript Small Basic, Gambas, Xojo
! Fortran, Basic Plus, Inform
; AutoHotkey, AutoIt, Lisp, Common Lisp, Clojure, Rebol, Scheme, many assemblers
-- Euphoria, Haskell, SQL, Ada, AppleScript, Eiffel, Lua, VHDL, SGML
* COBOL (if fixed-form and * in column 7), PAW, many assemblers, Fortran (if fixed-form and * in column 1)
|| Curl
" Vimscript
\ Forth

Block comments

Block comments are generally those that use a delimiter to indicate the beginning of a comment, and another delimiter to indicate the end of a comment. In this context, whitespace and newline characters are not counted as delimiters.


Symbol Languages
¢ ~ ¢,
# ~ #,co ~ co,
comment ~ comment
ALGOL 68[11][12]
/* ~ */ ActionScript, AutoHotkey, C, C++, C#, D,[13] Go, Java, JavaScript, Objective-C, PHP, PL/I, Rust (can be nested), Scala (can be nested), SASS, SQL, Swift, Visual Prolog, CSS
#cs ~ #ce AutoIt[14]
/+ ~ +/ D (can be nested)[13]
/# ~ #/ Cobra (can be nested)
<# ~ #> Powershell
=begin ~ =cut Perl
#`( ~ ) Perl6 (bracketing characters can be (), <>, {}, [], any Unicode characters with BiDi mirrorings, or Unicode characters with Ps/Pe/Pi/Pf properties)
=begin ~ =end Ruby
#<TAG> ~ #</TAG>, #stop ~ EOF,
#iffalse ~ #endif, #ifntrue ~ #endif,
#if false ~ #endif, #if !true ~ #endif
{- ~ -} Haskell (can be nested)
(* ~ *) Object Pascal (Delphi), ML, Mathematica, Pascal, Seed7, Applescript, OCaml (can be nested), Standard ML (can be nested), Maple, Newspeak
{ ~ } Object Pascal (Delphi), Pascal
|# ~ #| Curl
%{ ~ %} MATLAB[10] (the symbols must be in a separate line)
#| ~ |# Lisp, Scheme, Racket (can be nested in all three).
--[[</code> ~ <code>]],
--[=[ ~ ]=]
Lua (the former form can be nested, but only within the latter, which can't be nested)
" ~ " Smalltalk
(comment ~ ) Clojure

Unique variants











Scheme and Racket

Esoteric languages

Comment comparison

There is a wide variety of syntax styles for declaring comments in source code. BlockComment in italics is used here to indicate block comment style. InlineComment in italics is used here to indicate inline comment style.

Language In-line comment Block comment
Ada, Eiffel, Euphoria, Occam, SPARK, ANSI SQL, and VHDL -- InlineComment
ALGOL 60 comment BlockComment;
ALGOL 68 ¢ BlockComment ¢

comment BlockComment comment
co BlockComment co
# BlockComment #
£ BlockComment £

AppleScript -- InlineComment (* BlockComment *)
Assembly language (varies) ; InlineComment   one example (most assembly languages use line comments only)
AutoHotkey ; InlineComment /* BlockComment */
AWK, Bash, Bourne shell, C shell, Maple, R, Tcl, and Windows PowerShell # InlineComment <# BlockComment #>
BASIC (various dialects): 'InlineComment (not all dialects)

REM InlineComment

C (K&R, ANSI/C89/C90), CHILL, PL/I, and REXX /* BlockComment */
C (C99), C++, Go, and JavaScript // InlineComment /* BlockComment */
C# // InlineComment
/// InlineComment (XML documentation comment)
/* BlockComment */
/** BlockComment */ (XML documentation comment)
COBOL InlineComment (when * or / is in column 7)

*> InlineComment

Curl || InlineComment |# BlockComment #|

|foo# BlockComment #|

Cobra # InlineComment /# BlockComment #/ (nestable)
D // InlineComment
/// Documentation InlineComment (ddoc comments)
/* BlockComment */
/** Documentation BlockComment */ (ddoc comments)

/+ BlockComment +/ (nestable)
/++ Documentation BlockComment +/ (nestable, ddoc comments)

DCL $! InlineComment
ECMAScript (JavaScript, ActionScript, etc.) // InlineComment /* BlockComment */
Forth \ InlineComment ( BlockComment ) (single line only)

( before -- after ) stack comment convention

Fortran 66/77 C InlineComment (the letter 'C' in the first column makes the entire line a comment).
Fortran 90 ! InlineComment (all characters on the line, from the exclamation mark onwards, are comments)
Haskell -- InlineComment {- BlockComment -}
Java // InlineComment /* BlockComment */

/** BlockComment */ (Javadoc documentation comment)

Lisp and Scheme ; InlineComment #| BlockComment |#
Lua -- InlineComment --[==[ BlockComment]==] (variable number of = signs)
Maple # InlineComment (* BlockComment *)
Mathematica (* BlockComment *)
Matlab % InlineComment %{
BlockComment (nestable)

Note: Both percent–bracket symbols must be the only non-whitespace characters on their respective lines.
Object Pascal (Delphi) // InlineComment (* BlockComment *)
{ BlockComment }
OCaml (* BlockComment (* nestable *) *)
Pascal, Modula-2, Modula-3, Oberon, and ML: (* BlockComment *)
Perl and Ruby # InlineComment =begin
(=end in Ruby) (POD documentation comment)

Comments after end of code

PHP # InlineComment
// InlineComment
/* BlockComment */
/** Documentation BlockComment */ (PHP Doc comments)
PILOT R:InlineComment
PLZ/SYS ! BlockComment !
PL/SQL and TSQL -- InlineComment /* BlockComment */
Python # InlineComment ''' BlockComment '''
""" BlockComment """

(Documentation string when first line of module, class, method, or function)

Rust // InlineComment

/// InlineComment ("Outer" rustdoc comment)
//! InlineComment ("Inner" rustdoc comment)

/* BlockComment */ (nestable)

/** BlockComment */ ("Outer" rustdoc comment)
/*! BlockComment */ ("Inner" rustdoc comment)

SAS * BlockComment;
/* BlockComment */
Seed7 # InlineComment (* BlockComment *)
Simula comment BlockComment;
! BlockComment;
Smalltalk "BlockComment"
Smarty {* BlockComment *}
Standard ML (* BlockComment *)
TeX, LaTeX, PostScript, Erlang, and S-Lang % InlineComment
Texinfo @c InlineComment

@comment InlineComment

TUTOR * InlineComment
command $$ InlineComment
Visual Basic ' InlineComment
Rem InlineComment
Visual Basic .NET ' InlineComment

''' InlineComment (XML documentation comment)
Rem InlineComment

Visual Prolog % InlineComment /* BlockComment */
Wolfram Language (* BlockComment *)
Xojo ' InlineComment
// InlineComment
rem InlineComment

See also


  1. 1 2 For multiple statements on one line
  2. Three different kinds of clauses, each separates phrases and the units differently:
      1. serial-clause using go-on-token (viz. semicolon): begin a; b; c end – units are executed in order.
      2. collateral-clause using and-also-token (viz. “,”): begin a, b, c end – order of execution is to be optimised by the compiler.
      3. parallel-clause using and-also-token (viz. “,”): par begin a, b, c end – units must be run in parallel threads.
  3. semicolon – result of receding statement hidden, comma – result displayed
  4. Bash Reference Manual, Escape Character
  5. Python Documentation, 2. Lexical analysis: 2.1.5. Explicit line joining
  8. For an M-file (MATLAB source) to be accessible by name, its parent directory must be in the search path (or current directory).
  10. 1 2 "". Retrieved 25 June 2013.
  11. "Algol68_revised_report-AB.pdf on PDF page 61-62, original document page 121-122" (PDF). Retrieved 27 May 2014.
  12. "HTML Version of the Algol68 Revised Report AB". Retrieved 27 May 2014.
  13. 1 2 ", Lexical". Retrieved 27 May 2014.
  14. " Keyword Reference, #comments-start". Retrieved 27 May 2014.
  15. "slang-2.2.4/src/slprepr.c - line 43 to 113". Retrieved 28 May 2014.
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