C++ rand() why give me the same number How can i have different [duplicate]

This question already has an answer here:

• Why do I always get the same sequence of random numbers with rand()? 12 answers

if (ii == 3){//车辆只停了一个小时，有3/4的概率离场
    srand((unsigned)time(NULL)*100);
    int a = 1+rand() % 4;
    int b = 1+rand() % 4;
    int c = 1+rand() % 4;
    cout << "++++3 " << a << "++++" << endl;//用作测试判断是否离场函数
    cout << "++++3 " << b << "++++" << endl;
    cout << "++++3 " << c << "++++" << endl;
    cout << "*************" << endl;
    if ((a == 1 && b == 2 && c == 3)||(a==2&&b==1&&c==3)||(a==3&&b==2&&c==1)||(a==3&&b==2&&c==1))
        return true;
    else
        return false;
}![enter image description here][1]

just like this picture programe give me the same number ,but i need different,how can i do it.