This manual page is part of the POSIX Programmer’s Manual.
The Linux implementation of this interface may differ
(consult the corresponding Linux manual page for details of
Linux behavior), or the interface may not be implemented on

index − character string operations (LEGACY)

#include <strings.h>

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

The index() function shall be equivalent to strchr().

See strchr().

See strchr().

The following sections are informative.


The strchr() function is preferred over this function.

For maximum portability, it is recommended to replace the
function call to index() as follows:

     #define index(a,b) strchr((a),(b))


This function may be withdrawn in a future version.


strchr(), the Base Definitions volume of
IEEE Std 1003.1‐2001, <strings.h>

Portions of this text are reprinted and reproduced in
electronic form from IEEE Std 1003.1, 2003 Edition, Standard
for Information Technology ‐‐ Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001‐2003 by the Institute of Electrical
and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the
original IEEE and The Open Group Standard, the original IEEE
and The Open Group Standard is the referee document. The
original Standard can be obtained online at .