字符串所有子串（C++）

int _tmain(int argc, _TCHAR* argv[])
{
    //char *str = "abcbcabc";

    string str("abcbcabc");
    int len = strlen(str.c_str());
    for(int i = 1 ; i <= len ; i++){
        int s = 0 ;
        while(s<=len){
            string sub = str.substr(s,i);
            if(strlen(sub.c_str())==i)
                cout<<str.substr(s,i)<<endl;
            s++;
        }
        cout<<endl;
    }
    return 0;
}