Punctuation

These are the punctuation symbols in C. The meaning of each symbol is detailed in the linked pages.

{ }

• In a struct or union definition, delimit the struct-declaration-list.
• In an enum definition, delimit the enumerator list.
• Delimit a compound statement. The compound statement may be part of a function definition.
• In initialization, delimit the initializers.

[ ]

• Subscript operator.
• Part of array declarator in a declaration or a type-id.
• In initialization, introduce a designator for an array element. (since C99)
• In an attribute specifier, delimit the attributes. (since C23)

#

• Introduce a preprocessing directive.
• The preprocessing operator for stringification.

##

• The preprocessing operator for token pasting.

( )

• In an expression, indicate grouping.
• Function call operator.
• In a sizeof, _Alignof(since C11) , typeof or typeof_unqual(since C23) expression, delimit the operand.
• In an explicit cast, delimit the type-id.
• In a compound literal, delimit the type-id. (since C99)
• In a declaration or a type-id, indicate grouping.
• In a function declarator (in a declaration or a type-id), delimit the parameter list.
• In an if, switch, while, do-while, or for statement, delimit the controlling clause.
• In a function-like macro definition, delimit the macro parameters.
• In a function-like macro invocation, delimit the macro arguments or prevent commas from being interpreted as argument separators.
• Part of a defined, __has_include, __has_embed or __has_c_attribute(since C23) preprocessing operator.
• Part of a generic selection expression. (since C11)
• In an _Atomic type specifier, delimit the type-id. (since C11)
• In a static assertion declaration, delimit the operands. (since C11)
• In an _Alignas specifier, delimit the operand. (since C11)
• In an attribute, delimit the attribute arguments. (since C23)
• In a bit-precise integer type name (_BitInt(N)), delimit the size. (since C23)
• Part of __VA_OPT__ replacement in a variadic macro definition. (since C23)
• In a preprocessor parameter used in #embed directives and __has_embed preprocessing expressions, delimit the preprocessor parameter clause. (since C23)

;

• Indicate the end of
• a statement (including the init-statement of a for statement)
• a declaration or struct-declaration-list
• Separate the second and third clauses of a for statement.

:

• Part of conditional operator.
• Part of label declaration.
• In a bit-field member declaration, introduce the width.
• Introduce an enum base, which specifies the underlying type of the enum. (since C23)
• In a generic association, delimit the type-id or default and the selected expression. (since C11)

...

• In the parameter list of a function declarator, signify a variadic function.
• In a macro definition, signify a variadic macro. (since C99)

?

• Part of conditional operator.

::

• In an attribute, indicate attribute scope. (since C23)
• In a preprocessor prefixed parameter (used by #embed and __has_embed), indicate scope. (since C23)

.

• Member access operator.
• In initialization, introduce a designator for a struct/union member. (since C99)

->

• Member access operator.

~

• Unary complement operator (a.k.a. bitwise not operator).

!

• Logical not operator.

+

• Unary plus operator.
• Binary plus operator.

-

• Unary minus operator.
• Binary minus operator.

*

• Indirection operator.
• Multiplication operator.
• Pointer operator operator in a declarator or in a type-id.
• Placeholder for the length of a variable-length array declarator in a function declaration. (since C99)

/

• Division operator.

%

• Modulo operator.

^

• Bitwise xor operator.

&

• Address-of operator.
• Bitwise and operator.

|

• Bitwise or operator.

=

• Simple assignment operator.
• In initialization, delimit the object and the initializer list.
• In an enum definition, introduce the value of enumeration constant.

+=

• Compound assignment operator.

-=

• Compound assignment operator.

*=

• Compound assignment operator.

/=

• Compound assignment operator.

%=

• Compound assignment operator.

^=

• Compound assignment operator.

&=

• Compound assignment operator.

|=

• Compound assignment operator.

==

• Equality operator.

!=

• Inequality operator.

<

• Less-than operator.
• Introduce a header name in
• a #include directive
• a __has_include preprocessing expression (since C23)
• a #embed directive (since C23)
• a __has_embed preprocessing expression (since C23)
• implementation-defined locations within a #pragma directive

>

• Greater-than operator.
• Indicate the end of a header name in
• a #include directive
• a __has_include preprocessing expression (since C23)
• a #embed directive (since C23)
• a __has_embed preprocessing expression (since C23)
• implementation-defined locations within a #pragma directive

<=

• Less-than-or-equal-to operator.

>=

• Greater-than-or-equal-to operator.

&&

• Logical and operator.

||

• Logical or operator.

<<

• Bitwise shift operator.

>>

• Bitwise shift operator.

<<=

• Compound assignment operator.

>>=

• Compound assignment operator.

++

• Increment operator.

--

• Decrement operator.

,

• Comma operator.
• List separator in
• the declarator list in a declaration
• initializer list in initialization, including compound literals(since C99)
• the argument list in a function call expression
• the enumerator list in an enum declaration
• a function parameter list
• the macro parameter list in a function-like macro definition
• the macro argument list in a function-like macro invocation, unless found between an inner set of parentheses
• the generic association list in a generic selection expression (since C11)
• an attribute list (since C23)
• In a static assertion declaration, separate the arguments. (since C11)
• In a generic selection expression, separate the controlling expression and the generic association list. (since C11)

References

• C23 standard (ISO/IEC 9899:2023):
• 6.4.6 Punctuators (p: 68-69)
• C17 standard (ISO/IEC 9899:2018):
• 6.4.6 Punctuators (p: 52-53)
• C11 standard (ISO/IEC 9899:2011):
• 6.4.6 Punctuators (p: 72-73)
• C99 standard (ISO/IEC 9899:1999):
• 6.4.6 Punctuators (p: 63-64)
• C89/C90 standard (ISO/IEC 9899:1990):
• 3.1.6 Punctuators

See also