INDEX(3C)INDEX(3C)NAME
index, rindex - string operations
SYNOPSIS
#include <strings.h>
char *index(const char *s, int c);
char *rindex(const char *s, int c);
DESCRIPTION
The index() and rindex() functions operate on null-terminated strings.
The index() function returns a pointer to the first occurrence of char‐
acter c in string s.
The rindex() function returns a pointer to the last occurrence of char‐
acter c in string s.
Both index() and rindex() return a null pointer if c does not occur in
the string. The null character terminating a string is considered to be
part of the string.
USAGE
On most modern computer systems, you can not use a null pointer to
indicate a null string. A null pointer is an error and results in an
abort of the program. If you wish to indicate a null string, you must
use a pointer that points to an explicit null string. On some machines
and with some implementations of the C programming language, a null
pointer, if dereferenced, would yield a null string. Though often
used, this practice is not always portable. Programmers using a null
pointer to represent an empty string should be aware of this portabil‐
ity issue. Even on machines where dereferencing a null pointer does
not cause an abort of the program, it does not necessarily yield a null
string.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬─────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼─────────────────┤
│Interface Stability │ Standard │
└────────────────────┴─────────────────┘
SEE ALSObstring(3C), malloc(3C), string(3C), attributes(5), standards(5)
Jul 24, 2002 INDEX(3C)