STRCASECMP(3POSIX)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
strcasecmp, strcasecmp_l, strncasecmp, strncasecmp_l — case-insensitive string comparisons

SYNOPSIS

#include <strings.h>

int strcasecmp(const char *s1, const char *s2);
int strcasecmp_l(const char *s1, const char *s2,
    locale_t locale);
int strncasecmp(const char *s1, const char *s2, size_t n);
int strncasecmp_l(const char *s1, const char *s2,
    size_t n, locale_t locale);

DESCRIPTION
The strcasecmp() and strcasecmp_l() functions shall compare, while ignoring differences in case, the string pointed to by s1 to the string pointed to by s2. The strncasecmp() and strncasecmp_l() functions shall compare, while ignoring differences in case, not more than n bytes from the string pointed to by s1 to the string pointed to by s2.

The strcasecmp() and strncasecmp() functions use the current locale to determine the case of the characters.

The strcasecmp_l() and strncasecmp_l() functions use the locale represented by locale to determine the case of the characters.

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.

The behavior is undefined if the locale argument to strcasecmp_l() or strncasecmp_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

RETURN VALUE
Upon completion, strcasecmp() and strcasecmp_l() shall return an integer greater than, equal to, or less than 0, if the string pointed to by s1 is, ignoring case, greater than, equal to, or less than the string pointed to by s2, respectively.

Upon successful completion, strncasecmp() and strncasecmp_l() shall return an integer greater than, equal to, or less than 0, if the possibly null-terminated array pointed to by s1 is, ignoring case, greater than, equal to, or less than the possibly null-terminated array pointed to by s2, respectively.

ERRORS
No errors are defined.

The following sections are informative.

EXAMPLES
None.

APPLICATION USAGE
None.

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
wcscasecmp()

The Base Definitions volume of POSIX.1-2017, <strings.h>

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .