strcasecmp, strncasecmp - compare two strings ignoring case
#include <strings.h>
int strcasecmp(const char *s1, const char *s2);
int strncasecmp(const char *s1, const char *s2, size_t n);
The
strcasecmp() function performs a byte-by-byte comparison of the
strings
s1 and
s2, ignoring the case of the characters. It
returns an integer less than, equal to, or greater than zero if
s1 is
found, respectively, to be less than, to match, or be greater than
s2.
The
strncasecmp() function is similar, except that it compares no more
than
n bytes of
s1 and
s2.
The
strcasecmp() and
strncasecmp() functions return an integer
less than, equal to, or greater than zero if
s1 is, after ignoring
case, found to be less than, to match, or be greater than
s2,
respectively.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| strcasecmp (), strncasecmp () |
Thread safety |
MT-Safe locale |
4.4BSD, POSIX.1-2001, POSIX.1-2008.
The
strcasecmp() and
strncasecmp() functions first appeared in
4.4BSD, where they were declared in
<string.h>. Thus, for reasons
of historical compatibility, the glibc
<string.h> header file
also declares these functions, if the
_DEFAULT_SOURCE (or, in glibc
2.19 and earlier,
_BSD_SOURCE) feature test macro is defined.
The POSIX.1-2008 standard says of these functions:
When the LC_CTYPE category of the locale being
used is from the POSIX locale, these functions shall behave as if the strings
had been converted to lowercase and then a byte comparison performed.
Otherwise, the results are unspecified.
bcmp(3),
memcmp(3),
strcmp(3),
strcoll(3),
string(3),
strncmp(3),
wcscasecmp(3),
wcsncasecmp(3)