1STRSTR(3)                  Linux Programmer's Manual                 STRSTR(3)
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NAME

6       strstr, strcasestr - locate a substring
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SYNOPSIS

9       #include <string.h>
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11       char *strstr(const char *haystack, const char *needle);
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13       #define _GNU_SOURCE         /* See feature_test_macros(7) */
14       #include <string.h>
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16       char *strcasestr(const char *haystack, const char *needle);
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DESCRIPTION

19       The  strstr() function finds the first occurrence of the substring nee‐
20       dle in the string haystack.  The terminating null bytes ('\0') are  not
21       compared.
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23       The  strcasestr()  function  is  like strstr(), but ignores the case of
24       both arguments.
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RETURN VALUE

27       These functions return a pointer to the beginning of the  located  sub‐
28       string, or NULL if the substring is not found.
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30       If  needle is the empty string, the return value is always haystack it‐
31       self.
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ATTRIBUTES

34       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
35       tributes(7).
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37       ┌─────────────────────────────────────┬───────────────┬────────────────┐
38       │Interface                            │ Attribute     │ Value          │
39       ├─────────────────────────────────────┼───────────────┼────────────────┤
40       │strstr()                             │ Thread safety │ MT-Safe        │
41       ├─────────────────────────────────────┼───────────────┼────────────────┤
42       │strcasestr()                         │ Thread safety │ MT-Safe locale │
43       └─────────────────────────────────────┴───────────────┴────────────────┘
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CONFORMING TO

46       strstr(): POSIX.1-2001, POSIX.1-2008, C89, C99.
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48       The strcasestr() function is a nonstandard extension.
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SEE ALSO

51       index(3),  memchr(3),  memmem(3),  rindex(3), strcasecmp(3), strchr(3),
52       string(3), strpbrk(3), strsep(3), strspn(3), strtok(3), wcsstr(3)
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COLOPHON

55       This page is part of release 5.13 of the Linux  man-pages  project.   A
56       description  of  the project, information about reporting bugs, and the
57       latest    version    of    this    page,    can     be     found     at
58       https://www.kernel.org/doc/man-pages/.
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62GNU                               2021-08-27                         STRSTR(3)
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