c++ 随机数rand()必须结合srand(time(NULL))

int flag1 = 0;
    for(int i = 0;i <= 100000000;i++)
    {
            //srand(time(NULL));
            int a = rand()%101;
            if(a == 99)
            {
               flag1++; 
            }
    }
    cout<<flag1<<endl;
    /**************************/
    /*2*/
    int flag2 = 0;
    for(int i = 0;i <= 100000000;i++)
    {
            srand(time(NULL));
            int a = rand()%101;
            if(a == 99)
            {
               flag2++; 
            }
    }
     cout<<flag2<<endl;