roll the dice

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

int dice_sum, edge_sum;

class gameStart{
    string s;
    public:
        void dice_roll(string &str)
        {
            for(int j=0; j<str.find("d"); ++j){
                s +=str[j];
            }
            dice_sum = stoi(s);
            s.clear();
            for(int k=str.find("d")+1; str[k]!=NULL; ++k){
                s +=str[k];
            }
            edge_sum = stoi(s);
        }
};

int main()
{
    //input
    string str;
    cout << "Roll the dice: ";
    getline(cin, str);

    gameStart gs;
    gs.dice_roll(str);

    //output
    srand(time(0));
    for (int i=0; i < dice_sum; ++i){
    cout << 1 + rand() % edge_sum << endl;
    }

    return 0;
}