C Programming/C Reference/List of C functions
The predefined functions used in the C standard library, and a few other common functions, are listed below sorted by header file.
Standard library headers
assert.h
- assert (macro)
ctype.h
- digittoint (non-standard)
- isalnum
- isalpha
- isascii (non-standard)
- isblank
- iscntrl
- isdigit
- isgraph
- islower
- isprint
- ispunct
- isspace
- isupper
- isxdigit
- toascii (non-standard)
- tolower
- toupper
inttypes.h
- imaxabs
- imaxdiv
- strtoimax
- strtoumax
- wcstoimax
- wcstoumax
locale.h
- localeconv
- setlocale
setjmp.h
- longjmp
- setjmp
signal.h
- raise
stdarg.h
- va_arg (macro)
- va_copy (macro)
- va_end (macro)
- va_start (macro)
stddef.h
- offsetof (macro)
stdlib.h
- abort
- abs, labs
- atexit
- atof
- atoi
- atol
- bsearch
- div, ldiv
- exit
- free
- itoa (non-standard)
- getenv
- ltoa (non-standard)
- malloc, calloc, and realloc
- qsort
- rand
- srand
- strtod
- strtol
- strtoul
- system
string.h
- memchr
- memcmp
- memcpy
- memmove
- memset
- strcat, strncat
- strchr
- strcmp, strncmp
- strcoll
- strcpy, strncpy
- strcspn
- strerror
- strlen
- strpbrk
- strrchr
- strspn
- strstr
- strtok
- strxfrm
time.h
- asctime
- clock
- ctime
- difftime
- gmtime
- localtime
- mktime
- strftime
- time
wchar.h
- btowc
- fgetwc
- fgetws
- fputwc
- fputws
- fwide
- fwprintf
- fwscanf
- getwc (macro)
- getwchar (macro)
- mbrlen
- mbrtowc
- mbsinit
- mbsrtowcs
- putwc (macro)
- putwchar (macro)
- swprintf
- swscanf
- ungetwc
- vfwprintf
- vswprintf
- vwprintf
- wcrtomb
- wcscat
- wcschr
- wcscmp
- wcscoll
- wcscpy
- wcscspn
- wcsftime
- wcslen
- wcsncat
- wcsncmp
- wcsncpy
- wcspbrk
- wcsrchr
- wcsrtombs
- wcsspn
- wcsstr
- wcstod
- wcstok
- wcstol
- wcstoul
- wcsxfrm
- wctob
- wmemchr
- wmemcmp
- wmemcpy
- wmemmove
- wmemset
- wprintf
- wscanf
wctype.h
- iswalnum
- iswalpha
- iswcntrl
- iswctype
- iswdigit
- iswgraph
- iswlower
- iswprint
- iswpunct
- iswspace
- iswupper
- iswxdigit
- towctrans
- towlower
- towupper
- wctrans
- wctype
Non-standard headers
alloc.h
- farmalloc
conio.h
- getch
- getche
- gotoxy
netdb.h
- getaddrinfo
- getnameinfo