(C) Function

A function is "a named sequence of statements that can be invoked/called given arguments and that might return a value. The type of the function includes the number and types of argument and the type of the value returned, if any" [1].

[return type] [function name]( [arguments] )
{
  [statements]
}

A function has a declaration and a definition. The compiler needs to have read the function declaration before this function is used. If the definition is nowhere provided, this results in a linking error.

Functions can also be ?static. This means that it can only be called from its ?unit/module.

static void sayHello()
{
  std::cout << "Hello" << std::endl;
}

Functions without a return type specified

You should always specify a return type.

 myFunction() /* NO! No return type! */

In earlier implementations of C, there was a default return type of type int

Standard functions

?abort
?abs
?acos
?asctime
?asin
assert
?atan
?atan2
?atexit
?atof
?atoi
?atol
?bsearch
?calloc
?ceil
?clearerr
?clock
?cos
?cosh
?ctime
?difftime
?div
?exit
?exp
?fabs
fclose
?feof
?ferror
?fflush
?fgetc
?fgetpos
?fgets
?floor
?fmod
fopen
fprintf
?fputc
fputs
?fread
?free
?freopen
?frexp
fscanf
?fseek
?fsetpos
?ftell
?fwrite
?getc
?getchar
?getenv
?gets
?gmtime
?isalnum
?isalpha
?iscntrl
?isdigit
?isgraph
?islower
?isprint
?ispunct
?isspace
?isupper
?isxdigit
?labs
?ldexp
?ldiv
?localtime
?log
?log10
?longjmp
malloc
?memchr
memcmp
memcpy
memmove
?memset
?mktime
?modf
?perror
?pow
printf
?putc
?putchar
?puts
?qsort
?raise
rand
?realloc
?remove
?rename
?rewind
scanf
?setbuf
?setjmp
?setlocale
?setvbuf
?signal
?sin
?sinh
?sprintf
?sqrt
?srand
?sscanf
?strcat
strchr
?strcmp
?strcoll
?strcpy
?strcspn
?strerror
?strftime
?strlen
?strncat
?strncmp
?strncpy
?strpbrk
?strrchr
?strspn
?strstr
?strtod
?strtok
?strtol
?strtoul
?strxfrm
?system
?tan
?tanh
?time
?tmpfile
?tmpnam
?tolower
?toupper
?ungetc
?va_arg
?vfprintf
?vprintf
?vsprintf

'Function' links

References

1) Bjarne Stroustrup's C++ Glossary. http://www.research.att.com/~bs/glossary.html

last edited (May 11, 2007) by bilderbikkel, Number of views: 2580, Current Rev: 4 (Diff)

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