笔试题strstr()

#include <stdio.h>

const char *strstr(const char * src, const char * des) {
  const char *psrc = NULL;
  const char *pdes = NULL;
  
  if (!src || !des) {
    return src;
  }
  
  while (*src) {
  psrc = src;
  pdes = des;
    
  do 
  {
    if (!*pdes) {
      return src;
    }
  } while(*psrc++ == *pdes++);
      src++;
  }
    return NULL;
}




int main() {
  
   const char *a = "123456";
   const char *b = "34";
   const char *c=NULL ;
   c = strstr(a, b);
   printf ("c = %s", c);

   return 0;
}