C++随机数

闲来无事，学习下老朋友C++的随机数~

#include<iostream.h>
#include<time.h>
#include<stdlib.h>
const double MinProb=1.0/(RAND_MAX+1);
bool happened(double probability)//probability 0~1
{
    if(probability<=0)
    {
return false;
    }
    if(probability<MinProb)
    {
        return rand()==0&&happened(probability*(RAND_MAX+1));
    }
    if(rand()<=probability*(RAND_MAX+1))
    {
        return true;
    }
    return false;
}
long myrandom(long n)//产生0~n-1之间的等概率随机数
{
    int t=0;
    if(n<=RAND_MAX)
    {
        long r=RAND_MAX-(RAND_MAX+1)%n;//尾数
        t = rand();
        while ( t > r )
       {
            t = rand();
       }
        return t % n;
    }
    else
    {
        long r = n%(RAND_MAX+1);//余数
        if( happened( (double)r/n ) )//取到余数的概率
       {
            return n-r+myrandom(r);
       }
        else
       {
            return rand()+myrandom(n/(RAND_MAX+1))*(RAND_MAX+1);
       }
	}
}
	
int main(int argc, char* argv[])
{
	int num = 0;
	int result = 0;
	system("color 70");
	while(true){
		cout<<"输入一个你要玩耍的数字【1---任意】,如果想要抛弃我，请按0键"<<endl;
		cin>>num;
		cout<<endl;
		if(num == 0) {
			break;
		}
		while(num <= 0) {
			cout<<"不要闹，输入一个你要玩耍的数字【要大于1哦】"<<endl;
			cin>>num;
			cout<<endl;
		}
		result = myrandom(num);
		cout<<"根据你输入的数字，获取的随机数是："<<result<<endl;
		system("pause");
	}
	return 0;
}