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strcasestr(3) Library Functions Manual strcasestr(3)

NAME

strcasestr - string case-insensitive search substring

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

#define _GNU_SOURCE  // See feature_test_macros(7)
#include <string.h>
char *strcasestr(const char *haystack, const char *needle);

DESCRIPTION

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

RETURN VALUE

See strstr(3).

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
strcasestr () Thread safety MT-Safe locale

STANDARDS

GNU.

HISTORY

GNU.

SEE ALSO

string(3), strstr(3)

2026-05-16 Linux man-pages 6.19