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 nee-
dle in the string haystack. The terminating null bytes ('\0') are not
compared.
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 at-
tributes(7).
┌─────────────────────────────────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├─────────────────────────────────────┼───────────────┼────────────────┤
│strstr() │ Thread safety │ MT-Safe │
├─────────────────────────────────────┼───────────────┼────────────────┤
│strcasestr() │ Thread safety │ MT-Safe locale │
└─────────────────────────────────────┴───────────────┴────────────────┘
STANDARDS
strstr(): POSIX.1-2001, POSIX.1-2008, C99.
The strcasestr() function is a nonstandard extension.
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 6.03 2023-02-05 strstr(3)
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