Standard library header <string.h>

This header provides functions for handling null-terminated byte strings.

Macros
NULL	implementation-defined null pointer constant (macro constant)
Types
size_t	unsigned integer type returned by the sizeof operator (typedef)
Functions
String manipulation
strcpystrcpy_s (C11)	copies one string to another (function)
strncpystrncpy_s (C11)	copies a certain amount of characters from one string to another (function)
strcatstrcat_s (C11)	concatenates two strings (function)
strncatstrncat_s (C11)	concatenates a certain amount of characters of two strings (function)
strxfrm	transform a string so that strcmp would produce the same result as strcoll (function)
strdup (C23)	allocates a copy of a string (function)
strndup (C23)	allocates a copy of a string of specified size (function)
String examination
strlenstrnlen_s (C11)	returns the length of a given string (function)
strcmp	compares two strings (function)
strncmp	compares a certain amount of characters of two strings (function)
strcoll	compares two strings in accordance to the current locale (function)
strchr	finds the first occurrence of a character (function)
strrchr	finds the last occurrence of a character (function)
strspn	returns the length of the maximum initial segment that consists of only the characters found in another byte string (function)
strcspn	returns the length of the maximum initial segment that consists of only the characters not found in another byte string (function)
strpbrk	finds the first location of any character in one string, in another string (function)
strstr	finds the first occurrence of a substring of characters (function)
strtokstrtok_s (C11)	finds the next token in a byte string (function)
Character array manipulation
memchr	searches an array for the first occurrence of a character (function)
memcmp	compares two buffers (function)
memsetmemset_explicitmemset_s (C23)(C11)	fills a buffer with a character (function)
memcpymemcpy_s (C11)	copies one buffer to another (function)
memmovememmove_s (C11)	moves one buffer to another (function)
memccpy (C23)	copies one buffer to another, stopping after the specified delimiter (function)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (C11)(C11)	returns a text version of a given error code (function)

Synopsis

#define __STDC_VERSION_STRING_H__ 202311L

#define NULL /* see description */

typedef /* see description */ size_t;

void* memcpy(void* restrict s1, const void* restrict s2, size_t n);
void* memccpy(void* restrict s1, const void* restrict s2, int c, size_t n);
void* memmove(void* s1, const void* s2, size_t n);
char* strcpy(char* restrict s1, const char* restrict s2);
char* strncpy(char* restrict s1, const char* restrict s2, size_t n);
char* strdup(const char* s);
char* strndup(const char* s, size_t n);
char* strcat(char* restrict s1, const char* restrict s2);
char* strncat(char* restrict s1, const char* restrict s2, size_t n);
int memcmp(const void* s1, const void* s2, size_t n);
int strcmp(const char* s1, const char* s2);
int strcoll(const char* s1, const char* s2);
int strncmp(const char* s1, const char* s2, size_t n);
size_t strxfrm(char* restrict s1, const char* restrict s2, size_t n);
/*QVoid*/* memchr(/*QVoid*/* s, int c, size_t n);
/*QChar*/* strchr(/*QChar*/* s, int c);
size_t strcspn(const char* s1, const char* s2);
/*QChar*/* strpbrk(/*QChar*/* s1, const char* s2);
/*QChar*/* strrchr(/*QChar*/* s, int c);
size_t strspn(const char* s1, const char* s2);
/*QChar*/* strstr(/*QChar*/* s1, const char* s2);
char* strtok(char* restrict s1, const char* restrict s2);
void* memset(void* s, int c, size_t n);
void* memset_explicit(void* s, int c, size_t n);
char* strerror(int errnum);
size_t strlen(const char* s);
size_t strnlen(const char* s, size_t n);

Only if the implementation defines __STDC_LIB_EXT1__ and additionally the user code defines __STDC_WANT_LIB_EXT1__ before any inclusion of <string.h>:

#ifdef __STDC_WANT_LIB_EXT1__

tyepdef /* see description */ errno_t;
tyepdef /* see description */ rsize_t;

errno_t memcpy_s(void* restrict s1, rsize_t s1max, const void* restrict s2, rsize_t n);
errno_t memmove_s(void* s1, rsize_t s1max, const void* s2, rsize_t n);
errno_t strcpy_s(char* restrict s1, rsize_t s1max, const char* restrict s2);
errno_t strncpy_s(char* restrict s1, rsize_t s1max, const char* restrict s2, rsize_t n);
errno_t strcat_s(char* restrict s1, rsize_t s1max, const char* restrict s2);
errno_t strncat_s(char* restrict s1, rsize_t s1max, const char* restrict s2, rsize_t n);
char* strtok_s(char* restrict s1, rsize_t* restrict s1max,
               const char* restrict s2, char** restrict ptr);
errno_t memset_s(void* s, rsize_t smax, int c, rsize_t n)
errno_t strerror_s(char* s, rsize_t maxsize, errno_t errnum);
size_t strerrorlen_s(errno_t errnum);
size_t strnlen_s(const char* s, size_t maxsize);

#endif