Manpage of MEMCHR

MEMCHR

Section: Linux Programmer's Manual (3)
Updated: 2015-08-08
Index
 

NAME

memchr, memrchr, rawmemchr - scan memory for a character  

SYNOPSIS

#include <string.h>void *memchr(const void *s, int c, size_t n);void *memrchr(const void *s, int c, size_t n);void *rawmemchr(const void *s, int c);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

memrchr(), rawmemchr(): _GNU_SOURCE  

DESCRIPTION

The memchr() function scans the initial nbytes of the memory area pointed to by sfor the first instance of c. Both cand the bytes of the memory area pointed to by sare interpreted as unsigned char.

The memrchr() function is like the memchr() function, except that it searches backward from the end of the nbytes pointed to by sinstead of forward from the beginning.

The rawmemchr() function is similar to memchr(): it assumes (i.e., the programmer knows for certain) that an instance of clies somewhere in the memory area starting at the location pointed to by s, and so performs an optimized search for c(i.e., no use of a count argument to limit the range of the search). If an instance of cis not found, the results are unpredictable. The following call is a fast means of locating a string's terminating null byte:

char *p = rawmemchr(s, aq\0aq);
 

RETURN VALUE

The memchr() and memrchr() functions return a pointer to the matching byte or NULL if the character does not occur in the given memory area.

The rawmemchr() function returns a pointer to the matching byte, if one is found. If no matching byte is found, the result is unspecified.  

VERSIONS

rawmemchr() first appeared in glibc in version 2.1.

memrchr() first appeared in glibc in version 2.2.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
memchr(), memrchr(), rawmemchr() Thread safetyMT-Safe
 

CONFORMING TO

memchr(): POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.

The memrchr() function is a GNU extension, available since glibc 2.1.91.

The rawmemchr() function is a GNU extension, available since glibc 2.1.  

SEE ALSO

ffs(3), index(3), memmem(3), rindex(3), strchr(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), wmemchr(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
VERSIONS
ATTRIBUTES
CONFORMING TO
SEE ALSO

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Time: 22:27:47 GMT, June 20, 2016