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42 lines
1.0 KiB
C
42 lines
1.0 KiB
C
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/* Simple implementation of strstr for systems without it.
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This function is in the public domain. */
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/*
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@deftypefn Supplemental char* strstr (const char *@var{string}, const char *@var{sub})
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This function searches for the substring @var{sub} in the string
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@var{string}, not including the terminating null characters. A pointer
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to the first occurrence of @var{sub} is returned, or @code{NULL} if the
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substring is absent. If @var{sub} points to a string with zero
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length, the function returns @var{string}.
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@end deftypefn
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*/
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/* FIXME: The above description is ANSI compiliant. This routine has not
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been validated to comply with it. -fnf */
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#include <stddef.h>
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extern char *strchr (const char *, int);
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extern int strncmp (const void *, const void *, size_t);
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extern size_t strlen (const char *);
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char *
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strstr (const char *s1, const char *s2)
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{
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const char *p = s1;
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const size_t len = strlen (s2);
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for (; (p = strchr (p, *s2)) != 0; p++)
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{
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if (strncmp (p, s2, len) == 0)
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return (char *)p;
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}
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return (0);
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}
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