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.\" ========================================================================
.\"
.IX Title "OPENSSL_STRCASECMP 3ossl"
.TH OPENSSL_STRCASECMP 3ossl "2026-01-16" "3.5.1" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
OPENSSL_strcasecmp, OPENSSL_strncasecmp \- compare two strings ignoring case
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/crypto.h>
\&
\& int OPENSSL_strcasecmp(const char *s1, const char *s2);
\& int OPENSSL_strncasecmp(const char *s1, const char *s2, size_t n);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The OPENSSL_strcasecmp function performs a byte-by-byte comparison of the strings
\&\fBs1\fR and \fBs2\fR, ignoring the case of the characters.
.PP
The OPENSSL_strncasecmp function is similar, except that it compares no more than
\&\fBn\fR bytes of \fBs1\fR and \fBs2\fR.
.PP
In POSIX-compatible system and on Windows these functions use \*(L"C\*(R" locale for
case insensitive. Otherwise the comparison is done in current locale.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
Both functions return 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.
.SH "NOTES"
.IX Header "NOTES"
OpenSSL extensively uses case insensitive comparison of \s-1ASCII\s0 strings. Though
OpenSSL itself is locale-agnostic, the applications using OpenSSL libraries may
unpredictably suffer when they use localization (e.g. Turkish locale is
well-known with a specific I/i cases). These functions use C locale for string
comparison.
.SH "HISTORY"
.IX Header "HISTORY"
These functions were added in OpenSSL 3.0.3.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2022\-2024 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.
