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/*

FUNCTION

        <<strstr>>---find string segment

INDEX

        strstr

ANSI_SYNOPSIS

        #include <string.h>

        char *strstr(const char *<[s1]>, const char *<[s2]>);

TRAD_SYNOPSIS

        #include <string.h>

        char *strstr(<[s1]>, <[s2]>)

        char *<[s1]>;

        char *<[s2]>;

DESCRIPTION

        Locates the first occurence in the string pointed to by <[s1]> of

        the sequence of characters in the string pointed to by <[s2]>

        (excluding the terminating null  character).

RETURNS

        Returns a pointer to the located string segment, or a null

        pointer if the string <[s2]> is not found. If <[s2]> points to

        a string with zero length, the <[s1]> is returned.

PORTABILITY

<<strstr>> is ANSI C.

<<strstr>> requires no supporting OS subroutines.

QUICKREF

        strstr ansi pure

*/

#include <string.h>

char *

_DEFUN (strstr, (searchee, lookfor),

        _CONST char *searchee _AND

        _CONST char *lookfor)

{

  if (*searchee == 0)

    {

      if (*lookfor)

        return (char *) NULL;

      return (char *) searchee;

    }

  while (*searchee)

    {

      size_t i;

      i = 0;

      while (1)

        {

          if (lookfor[i] == 0)

            {

              return (char *) searchee;

            }

          if (lookfor[i] != searchee[i])

            {

              break;

            }

          i++;

        }

      searchee++;

    }

  return (char *) NULL;

}