index - Man Page

locate character in string


#include <strings.h>

char *index(const char *s, int c);
char *rindex(const char *s, int c);


The index() function returns a pointer to the first occurrence of the character c in the string s.

The rindex() function returns a pointer to the last occurrence of the character c in the string s.

The terminating null byte ('\0') is considered to be a part of the strings.

Return Value

The index() and rindex() functions return a pointer to the matched character or NULL if the character is not found.


For an explanation of the terms used in this section, see attributes(7).

index(), rindex()Thread safetyMT-Safe

Conforming to

4.3BSD; marked as LEGACY in POSIX.1-2001. POSIX.1-2008 removes the specifications of index() and rindex(), recommending strchr(3) and strrchr(3) instead.

See Also

memchr(3), strchr(3), string(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), strtok(3)


This page is part of release 5.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

Referenced By

memchr(3), strchr(3), string(3), strpbrk(3), strsep(3), strspn(3), strstr(3), strtok(3).

The man page rindex(3) is an alias of index(3).

2021-03-22 GNU Linux Programmer's Manual