1STRSTR(3) Linux Programmer's Manual STRSTR(3)
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6 strstr - locate a substring
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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
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15 #include <string.h>
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17 char *strcasestr(const char *haystack, const char *needle);
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20 The strstr() function finds the first occurrence of the substring nee‐
21 dle in the string haystack. The terminating `\0' characters are not
22 compared.
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24 The strcasestr() function is like strstr(), but ignores the case of
25 both arguments.
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28 These functions return a pointer to the beginning of the substring, or
29 NULL if the substring is not found.
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32 Early versions of Linux libc (like 4.5.26) would not allow an empty
33 needle argument for strstr(). Later versions (like 4.6.27) work cor‐
34 rectly, and return haystack when needle is empty.
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37 The strstr() function conforms to C89 and C99. The strcasestr() func‐
38 tion is a non-standard extension.
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41 index(3), memchr(3), rindex(3), strchr(3), strcasecmp(3), strpbrk(3),
42 strsep(3), strspn(3), strtok(3), wcsstr(3), feature_test_macros(7)
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46GNU 2005-04-05 STRSTR(3)