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 .