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.\"     @(#)strcasecmp.3	8.1 (Berkeley) 6/9/93
.\" $FreeBSD: head/lib/libc/string/strcasecmp.3 251069 2013-05-28 20:57:40Z emaste $
.\"
.Dd December 25, 2013
.Dt STRCASECMP 3
.Os
.Sh NAME
.Nm strcasecmp ,
.Nm strncasecmp
.Nd compare strings, ignoring case
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In strings.h
.Ft int
.Fn strcasecmp "const char *s1" "const char *s2"
.Ft int
.Fn strncasecmp "const char *s1" "const char *s2" "size_t len"
.Ft int
.Fn strcasecmp_l "const char *s1" "const char *s2" "locale_t locale"
.Ft int
.Fn strncasecmp_l "const char *s1" "const char *s2" "size_t len" "locale_t locale"
.Sh DESCRIPTION
The
.Fn strcasecmp ,
.Fn strcasecmp_l ,
.Fn strncasecmp ,
and
.Fn strncasecmp_l
functions
compare the null-terminated strings
.Fa s1
and
.Fa s2 .
.Pp
The
.Fn strncasecmp
function compares at most
.Fa len
characters.
The
.Fn strcasecmp_l
and
.Fn strncasecmp_l
functions do the same as their non-locale versions above, but take an
explicit
.Fa locale
rather than using the current locale.
.Sh RETURN VALUES
The functions
.Fn strcasecmp
and
.Fn strncasecmp
return an integer greater than, equal to, or less than 0,
depending on whether
.Fa s1
is lexicographically greater than, equal to, or less than
.Fa s2
after translation of each corresponding character to lower-case.
The strings themselves are not modified.
The comparison is done using unsigned characters, so that
.Sq Li \e200
is greater than
.Ql \e0 .
The functions
.Fn strcasecmp_l
and
.Fn strncasecmp_l
do the same but take explicit locales.
.Sh SEE ALSO
.Xr memcmp 3 ,
.Xr strcmp 3 ,
.Xr strcoll 3 ,
.Xr strxfrm 3 ,
.Xr tolower 3 ,
.Xr wcscasecmp 3
.Sh HISTORY
The
.Fn strcasecmp
and
.Fn strncasecmp
functions first appeared in
.Bx 4.4 .
Their prototypes existed previously in
.In string.h
before they were moved to
.In strings.h
for
.St -p1003.1-2001
compliance.
.Pp
The
.Fn strcasecmp_l
and
.Fn strncasecmp_l
functions conform to
.St -p1003.1-2008 .