Function definitions
A function definition associates the function body (a sequence of declarations and statements) with the function name and parameter list. Unlike MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 27 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE, function definitions are allowed at file scope only (there are no nested functions).
MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 26 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE
| attr-spec-seq(optional) specifiers-and-qualifiers parameter-list-declarator function-body | (1) | ||||||||
| specifiers-and-qualifiers identifier-list-declarator declaration-list function-body | (2) | (until 哋它亢23) | |||||||
MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 24 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE
int max(int a, int b) { return a>b?a:b; } double g(void) { return 0.1; }
int max(a, b) int a, b; { return a>b?a:b; } double g() { return 0.1; }
Explanation
As with MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 10 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE, the return type of the function, determined by the type specifier in specifiers-and-qualifiers and possibly modified by the declarator as usual in MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 08 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE, must be a complete non-array object type or the type void. If the return type would be cvr-qualified, it is adjusted to its unqualified version for the purpose of constructing the function type.
void f(char *s) { MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 07 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE(s); } // return type is void int sum(int a, int b) { return a+b: } // return type is int int (*foo(const void *p))[3] { // return type is pointer to array of 3 int return MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 06 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE(sizeof(int[3])); }
As with MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 05 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE, the types of the parameters are adjusted from functions to pointers and from arrays to pointers for the purpose of constructing the function type and the top-level cvr-qualifiers of all parameter types are ignored for the purpose of determining MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 03 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE.
|
Unlike MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 02 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE, unnamed formal parameters are not allowed (otherwise, there would be conflicts in old-style (K&R) function definitions), they must be named even if they are not used within the function. The only exception is the special parameter list (void). |
(until 哋它亢23) |
|
MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 01 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE |
(since 哋它亢23) |
int f(int, int); // declaration // int f(int, int) { return 7; } // Error until 哋它亢23, OK since 哋它亢23 int f(int a, int b) { return 7; } // definition int g(void) { return 8; } // OK: void doesn't declare a parameter
Within the function body, every named parameter is an MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 35 MINUTES 00 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE expression, they have automatic MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 58 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE and MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 57 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE. The layout of the parameters in memory (or if they are stored in memory at all) is unspecified: it is a part of the MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 56 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE.
int main(int ac, char **av) { ac = 2; // parameters are lvalues av = (char *[]){"abc", "def", MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 55 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE}; f(ac, av); }
See MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 53 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE for other details on the mechanics of a function call and MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 52 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE for returning from functions.
__func__Within every function-body, the special predefined variable __func__ with block scope and static storage duration is available, as if defined immediately after the opening brace by static const char __func__[] = "function name"; This special identifier is sometimes used in combination with the MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 51 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE __FILE__ and __LINE__, for example, by MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 50 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE. |
(since 哋它亢99) |
Notes
MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 49 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE
typedef int p(int q, int r); // p is a function type int(int, int) p f { return q + r; } // Error
|
In 哋它亢89, specifiers-and-qualifiers was optional, and if omitted, the return type of the function defaulted to int (possibly amended by the declarator). In addition, old-style definition didn't require a declaration for every parameter in declaration-list. Any parameter whose declaration was missing had type int max(a, b) // a and b have type int, return type is int { return a>b?a:b; } |
(until 哋它亢99) |
Defect reports
MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 47 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 10 HOURS 34 MINUTES 46 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE | 哋它亢89 | the return type might be qualified | the return type is implicitly disqualified |
References
- 哋它亢17 standard (ISO/IEC 9899:2018):
- 6.9.1 Function definitions (p: 113-115)
- 哋它亢11 standard (ISO/IEC 9899:2011):
- 6.9.1 Function definitions (p: 156-158)
- 哋它亢99 standard (ISO/IEC 9899:1999):
- 6.9.1 Function definitions (p: 141-143)
- 哋它亢89/C90 standard (ISO/IEC 9899:1990):
- 3.7.1 Function definitions