The string.h header file declares the string manipulation functions and their built-in versions:
No feature test macro required.
| memchr()[1] | memcmp()[1] | memcpy()[1] | memmove() | memset()[1] |
| strcat()[1] | strchr()[1] | strcmp()[1] | strcoll() | strcpy()[1] |
| strcspn() | strerror() | strlen()[1] | strncat()[1] | strncmp()[1] |
| strncpy()[1] | strpbrk() | strrchr()[1] | strspn() | strstr() |
| strtok() | strxfrm() |
| strerror_r |
[1] Built-in function.
_XOPEN_SOURCE
| memccpy() |
_XOPEN_SOURCE_EXTENDED 1
| strdup() |
The string.h header file also defines the macro NULL and the type size_t. For more information see stddef.h.