C ++编号生成器输出相同的数字

Question

我正在制作一个模拟骰子滚动100次的程序，并跟踪每个数字的滚动次数。问题是数字生成器一直在反复输出相同的数字。它将它们加在一起很好，但它只是一个输出的数字。这是代码：

#include <iostream>
#include <cstdlib>
#include <cmath>
using namespace std;

int Diceroll (int);
int main() {

    int num = 0, sum1 = 0, sum2 = 0, sum3 = 0, sum4 = 0, sum5 = 0, sum6 = 0;
    int i = 0, j = 100;

    for(int i = 0; i < j; i++) {
         num = 0;

         num = Diceroll(num);
         cout << num << endl;

         if(num == 1) {
             sum1 += 1;
         }
         else if(num == 2) {
             sum2 += 1;
         }
         else if(num == 3) {
             sum3++;
         }
         else if(num == 4) {
             sum4++;
         }
         else if(num == 5) {
             sum5++;
         }
         else if(num == 6) {
             sum6++;
         }
    }

    cout << "1 was rolled " << sum1 << " times." << endl;
    cout << "2 was rolled " << sum2 << " times." << endl;
    cout << "3 was rolled " << sum3 << " times." << endl;
    cout << "4 was rolled " << sum4 << " times." << endl;
    cout << "5 was rolled " << sum5 << " times." << endl;
    cout << "6 was rolled " << sum6 << " times." << endl;

    return 0;
}

int Diceroll (int num) {

    srand(time(0));

    num = (rand()%6) + 1; 

    return num;
}