C Standard Library
C Standard Library
C standard headers, common types, macros, and the main families of C library functions.
C Standard Library
C standard headers, common types, macros, and the main families of C library functions.
Use reference pages to confirm names, categories, nearby facilities, and the constraints that matter before writing or reviewing code.
If you want the headers grouped as a fast index first, use C standard headers index.
<assert.h>assert<errno.h>errnoEDOM, ERANGE, and platform-defined values<stddef.h>size_t, ptrdiff_t, wchar_t, max_align_t, NULL, offsetof<stdint.h>int8_t, uint32_t, intmax_t, intptr_tINT32_C, UINT64_C<stdbool.h>bool, true, false<stdalign.h> and <stdnoreturn.h><stdlib.h>malloc, calloc, realloc, freeatoi, strtol, strtoul, strtod, strtofexit, abort, atexit, getenv, systemqsort, bsearchabs, labs, llabs, div, ldiv, lldiv<string.h>memcpy, memmove, memset, memcmp, memchrstrlen, strchr, strrchr, strstr, strpbrkstrcpy, strncpy, strcat, strncatstrcmp, strncmp, strtok, strcoll, strxfrmstrerror<ctype.h>isalpha, isdigit, isspace, isalnum, isxdigittolower, toupper<stdio.h>FILE, fopen, fclose, fflush, freopenprintf, fprintf, sprintf, snprintf, scanf, fscanf, sscanffgetc, getc, getchar, fputc, putc, putchar, fgets, fputs, putsfread, fwritefseek, ftell, rewind, fgetpos, fsetposperror, feof, ferror, tmpfile, tmpnam, remove, rename<stdarg.h>va_list, va_start, va_arg, va_copy, va_end<time.h>time_t, clock_t, struct tmtime, clock, difftime, mktime, strftime, gmtime, localtime, asctime, ctime<math.h>sin, cos, tan, asin, acos, atan, atan2exp, log, log10, pow, sqrt, cbrtfloor, ceil, round, trunc, fmod, remainderisfinite, isnan, signbit, fpclassify<locale.h>setlocale, localeconv, struct lconv<signal.h>signal, raise, sig_atomic_tSIGINT, SIGTERM, SIGABRT<stdatomic.h><threads.h>thrd_t, mtx_t, cnd_t, tss_tthrd_create, thrd_join, mutex and condition-variable operations<uchar.h>char16_t, char32_tThe C standard library is defined by headers, macros, types, and function families. In real code, always confirm exact signatures and platform-specific behavior before relying on edge-case semantics.
#include <vector>
#include <algorithm>
int main() {
std::vector<int> values{4, 1, 3, 2};
std::sort(values.begin(), values.end());
}