stristr.c

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/*
** Designation:  StriStr
**
** Call syntax:  char *stristr(char *String, char *Pattern)
**
** Description:  This function is an ANSI version of strstr() with
**               case insensitivity.
**
** Return item:  char *pointer if Pattern is found in String, else
**               pointer to 0
**
** Rev History:  16/07/97  Greg Thayer  Optimized
**               07/04/95  Bob Stout    ANSI-fy
**               02/03/94  Fred Cole    Original
**               09/01/03  Bob Stout    Bug fix (lines 40-41) per Fred Bulback
**
** Hereby donated to public domain.
*/

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "snip_str.h"

typedef unsigned int uint;

#if defined(__cplusplus) && __cplusplus
 extern "C" {
#endif

char *stristr(const char *String, const char *Pattern)
{
      char *pptr, *sptr, *start;

      for (start = (char *)String; *start != NUL; start++)
      {
            /* find start of pattern in string */
            for ( ; ((*start!=NUL) && (toupper(*start) != toupper(*Pattern))); start++)
                  ;
            if (NUL == *start)
                  return NULL;

            pptr = (char *)Pattern;
            sptr = (char *)start;

            while (toupper(*sptr) == toupper(*pptr))
            {
                  sptr++;
                  pptr++;

                  /* if end of pattern then pattern was found */

                  if (NUL == *pptr)
                        return (start);
            }
      }
      return NULL;
}

#if defined(__cplusplus) && __cplusplus
 }
#endif

#ifdef TEST

int main(void)
{
      int i;
      char *buffer[2] = {"heLLo, HELLO, hello, hELLo, HellO", "Hell"};
      char *sptr;

      for (i = 0; i < 2; ++i)
      {
            printf("\nTest string=\"%s\"\n", sptr = buffer[i]);
            while (0 != (sptr = stristr(sptr, "hello")))
            {
                  printf("Testing %s:\n", sptr);
                  printf("Found %5.5s!\n", sptr++);
            }
      }

      return(0);
}

#endif /* TEST */