INDEX(3C) Standard C Library Functions 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
character
c in string
s.
The
rindex() function returns a pointer to the last occurrence of
character
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
portability 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(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
SEE ALSO
bstring(3C),
malloc(3C),
string(3C),
attributes(7),
standards(7) July 24, 2002 INDEX(3C)
