#include <iostream>

 #include <cstdio>

 using namespace std;

 char *strstring(char *ParentString,char *SubString)

 {

     char *pSubString,*pParentString;

     for(char *pTmp = ParentString; *pTmp !='\0' ; pTmp++)

     {

         pSubString = SubString;

         pParentString = pTmp;

         while(*pSubString != '\0' && *pSubString == *pParentString)

         {

             pSubString++;

             pParentString++;

         }

         if(*pSubString == '\0')

         {

             return pTmp;

         }

     }

     return NULL;

 }

 int main()

 {

     cout << "Hello world!" << endl;

     char *ParentString = "I love TrendMicro!";

     char *SubString = "Trend";

     printf("%s\n",strstring(ParentString,SubString));

     return ;

 }