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strcasecmp(3) — Linux manual page

strcasecmp(3)            Library Functions Manualstrcasecmp(3)

NAME        top

       strcasecmp, strncasecmp - compare two strings ignoring case

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <strings.h>int strcasecmp(const char *s1, const char *s2);int strncasecmp(size_t n;const chars1[n], const chars2[n], size_tn);

DESCRIPTION        top

       Thestrcasecmp() function performs a byte-by-byte comparison of       the stringss1 ands2, ignoring the case of the characters.  It       returns an integer less than, equal to, or greater than zero ifs1       is found, respectively, to be less than, to match, or be greater       thans2.       Thestrncasecmp() function is similar, except that it compares no       more thann bytes ofs1 ands2.

RETURN VALUE        top

       Thestrcasecmp() andstrncasecmp() functions return an integer       less than, equal to, or greater than zero ifs1 is, after ignoring       case, found to be less than, to match, or be greater thans2,       respectively.

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌───────────────────────────────┬───────────────┬────────────────┐       │Interface│Attribute│Value│       ├───────────────────────────────┼───────────────┼────────────────┤       │strcasecmp(),strncasecmp()   │ Thread safety │ MT-Safe locale │       └───────────────────────────────┴───────────────┴────────────────┘

STANDARDS        top

       POSIX.1-2008.

HISTORY        top

       4.4BSD, POSIX.1-2001.       Thestrcasecmp() andstrncasecmp() 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 theLC_CTYPEcategory 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.

SEE ALSO        top

memcmp(3),strcmp(3),strcoll(3),string(3),strncmp(3),wcscasecmp(3),wcsncasecmp(3)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-06-28strcasecmp(3)

Pages that refer to this page:memcmp(3), strcmp(3), strcoll(3), string(3), strstr(3), strverscmp(3), strxfrm(3), wcscasecmp(3)

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