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Section: Standard C Library Functions (3C)
Updated: 24 Jul 2002
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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(5) for descriptions of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard

 

SEE ALSO

bstring(3C), malloc(3C), string(3C), attributes(5), standards(5)


 

Index

NAME
SYNOPSIS
DESCRIPTION
USAGE
ATTRIBUTES
SEE ALSO

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