Description

string.h is a standard header declaring prototypes for several functions that are useful for dealing with strings and untyped memory, as well as defining the NULL macro and the size_t type.

Implementation

A possible implementation is:

#ifndef _STRING_H
#define _STRING_H

#ifndef NULL
#define NULL 0
#endif

#ifndef _SIZE_T
#define _SIZE_T
typedef __np_size_t size_t;
#endif

void   *memchr(const void *, int, size_t);
int     memcmp(const void *, const void *, size_t);
void   *memcpy(void *_NC_RESTRICT, const void *_NC_RESTRICT, size_t);
void   *memmove(void *, const void *, size_t);
void   *memset(void *, int, size_t);
char   *strcat(char *_NC_RESTRICT, const char *_NC_RESTRICT);
char   *strchr(const char *, int);
int     strcmp(const char *, const char *);
int     strcoll(const char *, const char *);
char   *strcpy(char *_NC_RESTRICT, const char *_NC_RESTRICT);
size_t  strcspn(const char *, const char *);
char   *strerror(int);
size_t  strlen(const char *);
char   *strncat(char *_NC_RESTRICT, const char *_NC_RESTRICT, size_t);
int     strncmp(const char *, const char *, size_t);
char   *strncpy(char *_NC_RESTRICT, const char *_NC_RESTRICT, size_t);
char   *strpbrk(const char *, const char *);
char   *strrchr(const char *, int);
size_t  strspn(const char *, const char *);
char   *strstr(const char *, const char *);
char   *strtok(char *_NC_RESTRICT, const char *_NC_RESTRICT);
size_t  strxfrm(char *_NC_RESTRICT, const char *_NC_RESTRICT, size_t);

#endif /* _STRING_H */

Incomplete header, portable in implementation namespace; public domain; past reviewers: none; current reviews: none

Non-portable components

• __np_size_t
• _NC_RESTRICT

Common extensions

Many of the extensions listed below are mandated by one or more versions of the POSIX/SUS standards. None of them are covered by the C Standard and none is universally supported by C implementations or with necessarily universal semantics. For these reasons they aren't a focus for this wiki: don't rely on the accuracy or completeness of the information below.

void *memccpy(void *restrict, const void *restrict, int, size_t);
char *strdup(const char *);
int   strerror_r(int, char *, size_t);
char *strtok_r(char *, const char *, char **);

References

• The C Standard, 7.21 (C99 numbering)
• Dinkumware, Ltd C99 Library Reference: <string.h>