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Standard C Library Functionsindex(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.

SEE ALSO

 

bstring(3C), malloc(3C), string(3C)


SunOS 5.9Go To TopLast Changed 3 Mar 1996

 
      
      
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