bcmp(3) [xfree86 man page]

BCMP(3)                                                      Linux Programmer's Manual                                                     BCMP(3)

NAME

       bcmp - compare byte sequences

SYNOPSIS

       #include <strings.h>

       int bcmp(const void *s1, const void *s2, size_t n);

DESCRIPTION

       The  bcmp() function compares the two byte sequences s1 and s2 of length n each.  If they are equal, and in particular if n is zero, bcmp()
       returns 0.  Otherwise, it returns a nonzero result.

RETURN VALUE

       The bcmp() function returns 0 if the byte sequences are equal, otherwise a nonzero result is returned.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +----------+---------------+---------+
       |Interface | Attribute     | Value   |
       +----------+---------------+---------+
       |bcmp()    | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO

       4.3BSD.  This function is deprecated (marked as LEGACY in POSIX.1-2001): use memcmp(3) in new programs.  POSIX.1-2008 removes the  specifi-
       cation of bcmp().

SEE ALSO

       bstring(3), memcmp(3), strcasecmp(3), strcmp(3), strcoll(3), strncasecmp(3), strncmp(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux                                                               2017-03-13                                                             BCMP(3)

MEMCMP(3)						     Linux Programmer's Manual							 MEMCMP(3)

NAME

       memcmp - compare memory areas

SYNOPSIS

       #include <string.h>

       int memcmp(const void *s1, const void *s2, size_t n);

DESCRIPTION

       The memcmp() function compares the first n bytes (each interpreted as unsigned char) of the memory areas s1 and s2.

RETURN VALUE

       The memcmp() function returns an integer less than, equal to, or greater than zero if the first n bytes of s1 is found, respectively, to be
       less than, to match, or be greater than the first n bytes of s2.

       For a nonzero return value, the sign is determined by the sign of the difference between the first pair of bytes (interpreted  as  unsigned
       char) that differ in s1 and s2.

       If n is zero, the return value is zero.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +----------+---------------+---------+
       |Interface | Attribute	  | Value   |
       +----------+---------------+---------+
       |memcmp()  | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.

NOTES

       Do  not	use memcmp() to compare security critical data, such as cryptographic secrets, because the required CPU time depends on the number
       of equal bytes.	Instead, a function that performs comparisons in constant time is required.  Some operating systems provide such  a  func-
       tion  (e.g., NetBSD's consttime_memequal()), but no such function is specified in POSIX.  On Linux, it may be necessary to implement such a
       function oneself.

SEE ALSO

       bcmp(3), bstring(3), strcasecmp(3), strcmp(3), strcoll(3), strncasecmp(3), strncmp(3), wmemcmp(3)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

								    2017-09-15								 MEMCMP(3)