memchr(3) Library Functions Manual memchr(3)
NAME
memchr, memrchr, rawmemchr - scan memory for a character
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <string.h>
void *memchr(const void s[.n], int c, size_t n);
void *memrchr(const void s[.n], int c, size_t n);
[[deprecated]] 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 n bytes of the memory area
pointed to by s for the first instance of c. Both c and the bytes of
the memory area pointed to by s are interpreted as unsigned char.
The memrchr() function is like the memchr() function, except that it
searches backward from the end of the n bytes pointed to by s instead
of forward from the beginning.
The rawmemchr() function is similar to memchr(), but it assumes (i.e.,
the programmer knows for certain) that an instance of c lies somewhere
in the memory area starting at the location pointed to by s. If an in-
stance of c is not found, the behavior is undefined. Use either
strlen(3) or memchr(3) instead.
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.
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌───────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────────────────┼───────────────┼─────────┤
│ memchr(), memrchr(), rawmemchr() │ Thread safety │ MT-Safe │
└───────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
memchr()
C11, POSIX.1-2008.
memrchr()
rawmemchr()
GNU.
HISTORY
memchr()
POSIX.1-2001, C89, SVr4, 4.3BSD.
memrchr()
glibc 2.2.
rawmemchr()
glibc 2.1.
SEE ALSO
bstring(3), ffs(3), memmem(3), strchr(3), strpbrk(3), strrchr(3),
strsep(3), strspn(3), strstr(3), wmemchr(3)
Linux man-pages 6.7 2023-10-31 memchr(3)
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