IT公司面试手册

实现strstr功能，即在父串中寻找子串首次出现的位置。（笔试中常让面试者实现标准库中的一些函数）
char * strstring(char *ParentString, char *SubString) {
 char *pSubString, *pPareString;
 for(char *pTmp=ParentString; *pTmp; pTmp++) {
  pSubString = SubString;
  pPareString = pTmp; 
  while(*pSubString == *pPareString && *pSubString != ‘\0′) {
   pSubString++;
   pPareString++;
  }
  if(*pSubString == ‘\0′)  return pTmp;
 }
 return NULL;
}

int main(int argc, char* argv[]) {
 char *ParentString = “happy birthday to you!”;
 char *SubString = “birthday”;
 printf(“%s”,strstring(ParentString, SubString));
}