index(3)

index3

Locate character in string

Usage

#include <strings.h>

char *

index(const char *s, int c);

char *

rindex(const char *s, int c);

Library

Standard C Library (libc, -lc)

Overview

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 ‘\0’, the functions locate the terminating ‘\0’.

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.

Releases

163 releases since Mac OS X 10.0; the text changed 5 times.

  1. 10.0–10.1.5
  2. 10.2–10.2.8
  3. 10.3–10.3.9
  4. 10.4–10.4.11
  5. 10.5–10.6.8
  6. 10.7–26.5

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.

From Libc 1752.120.2 in macOS 26.5. Parsed by carta from the page's mdoc source.