strcasestr(3) — Linux manual page

strcasestr(3)            Library Functions Manual           strcasestr(3)

NAME         top

       strcasestr - string case-insensitive search substring

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #define _GNU_SOURCE  // See feature_test_macros(7)
       #include <string.h>

       char *strcasestr(const char *haystack, const char *needle);

DESCRIPTION         top

       strcasestr() is like strstr(), but ignores the case of both
       arguments.

RETURN VALUE         top

       See strstr(3).

ATTRIBUTES         top

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

STANDARDS         top

       GNU.

HISTORY         top

       GNU.

SEE ALSO         top

       string(3), strstr(3)

COLOPHON         top

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Linux man-pages 6.19            2026-05-16                  strcasestr(3)

Pages that refer to this page: string(3),  strstr(3)

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