strcasecmp(3) — Linux manual page

strcasecmp(3)           Library Functions Manual           strcasecmp(3)

NAME

       strcasecmp, strncasecmp - compare two strings ignoring case

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <strings.h>

       int strcasecmp(const char *s1, const char *s2);
       int strncasecmp(const char s1[.n], const char s2[.n], size_t n);

DESCRIPTION

       The strcasecmp() function performs a byte-by-byte comparison of
       the strings s1 and s2, ignoring the case of the characters.  It
       returns 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.

       The strncasecmp() function is similar, except that it compares no
       more than n bytes of s1 and s2.

RETURN VALUE

       The strcasecmp() and strncasecmp() functions return an integer
       less than, equal to, or greater than zero if s1 is, after
       ignoring case, found to be less than, to match, or be greater
       than s2, respectively.

ATTRIBUTES

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

STANDARDS

       POSIX.1-2008.

HISTORY

       4.4BSD, POSIX.1-2001.

       The strcasecmp() and strncasecmp() 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 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.

SEE ALSO

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

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                  strcasecmp(3)

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

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