strcasestr.c

   1 /*
   2  * Copyright (C) 2002     Manuel Novoa III
   3  * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
   4  *
   5  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
   6  */
   7 #include <stdlib.h>
   8 #include <ctype.h>
   9
  10 char *strcasestr(const char *s1, const char *s2)
  11 {
  12         register const char *s = s1;
  13         register const char *p = s2;
  14
  15 #if 1
  16         do {
  17                 if (!*p) {
  18                         return (char *) s1;;
  19                 }
  20                 if ((*p == *s)
  21                         || (tolower(*((unsigned char *)p)) == tolower(*((unsigned char *)s)))
  22                         ) {
  23                         ++p;
  24                         ++s;
  25                 } else {
  26                         p = s2;
  27                         if (!*s) {
  28                                 return NULL;
  29                         }
  30                         s = ++s1;
  31                 }
  32         } while (1);
  33 #else
  34         while (*p && *s) {
  35                 if ((*p == *s)
  36                         || (tolower(*((unsigned char *)p)) == tolower(*((unsigned char *)s)))
  37                         ) {
  38                         ++p;
  39                         ++s;
  40                 } else {
  41                         p = s2;
  42                         s = ++s1;
  43                 }
  44         }
  45
  46         return (*p) ? NULL : (char *) s1;
  47 #endif
  48 }