strstr(3) Library Functions Manual strstr(3)
NAME
strstr, strcasestr - locate a substring
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <string.h>
char *strstr(const char *haystack, const char *needle);
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <string.h>
char *strcasestr(const char *haystack, const char *needle);
DESCRIPTION
The strstr() function finds the first occurrence of the substring needle
in the string haystack. The terminating null bytes ('\0') are not com-
pared.
The strcasestr() function is like strstr(), but ignores the case of both
arguments.
RETURN VALUE
These functions return a pointer to the beginning of the located sub-
string, or NULL if the substring is not found.
If needle is the empty string, the return value is always haystack it-
self.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌─────────────────────────────────────┬───────────────┬────────────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────────────────┼───────────────┼────────────────┤
│ strstr() │ Thread safety │ MT-Safe │
├─────────────────────────────────────┼───────────────┼────────────────┤
│ strcasestr() │ Thread safety │ MT-Safe locale │
└─────────────────────────────────────┴───────────────┴────────────────┘
STANDARDS
strstr()
C11, POSIX.1-2008.
strcasestr()
GNU.
HISTORY
strstr()
POSIX.1-2001, C89.
strcasestr()
GNU.
SEE ALSO
memchr(3), memmem(3), strcasecmp(3), strchr(3), string(3), strpbrk(3),
strsep(3), strspn(3), strtok(3), wcsstr(3)
Linux man-pages 6.9.1 2024-06-15 strstr(3)
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