mojave man page for index

INDEX(3)						   BSD Library Functions Manual 						  INDEX(3)

NAME
     index, rindex -- locate character in string

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <strings.h>

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

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

DESCRIPTION
     The index() function locates the first occurrence of c (converted to a char) in the string pointed to by s.  The terminating null character
     is considered to be part of the string; therefore, if c is '', the functions locate the terminating ''.

     The rindex() function is identical to index(), except that it locates the last occurrence of c.

RETURN VALUES
     The functions index() and rindex() return a pointer to the located character, or NULL if the character does not appear in the string.

SEE ALSO
     memchr(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), strtok(3)

HISTORY
     The index() and rindex() functions appeared in Version 6 AT&T UNIX.  Their prototypes existed previously in <string.h> before they were moved
     to <strings.h> for IEEE Std 1003.1-2001 (``POSIX.1'') compliance.

BSD
								   June 4, 1993 							       BSD