随机数引擎和分布

17.28 编写函数，每次调用生成并返回一个均匀分布的随机unsigned int。

                                                                                                                                                                
#include<iostream>
#include<vector>
#include<random>
#include<ctime>
using namespace std;

int main()
{
    uniform_int_distribution<unsigned> u;
    default_random_engine e();
    for(size_t i=0;i<10;++i)
        cout<<u(e)<<" ";
    cout<<endl;
    for(size_t i=0;i<10;++i)
        cout<<u(e)<<" ";
    cout<<endl;
}

17.29 允许用户提供一个种子作为可选参数。

 17_29.cpp                                                                                                                                                                       
#include<iostream>
#include<vector>
#include<random>
#include<ctime>
using namespace std;

int main()
{
    uniform_int_distribution<unsigned> u;
    default_random_engine e(time(0));
    for(size_t i=0;i<10;++i)
        cout<<u(e)<<" ";
    cout<<endl;
    for(size_t i=0;i<10;++i)
        cout<<u(e)<<" ";
    cout<<endl;
}

17.30 此次增加两个参数，表示函数允许返回的最小值和最大值

#include<iostream>
#include<vector>
#include<random>
#include<ctime>
using namespace std;

int main()
{
    uniform_int_distribution<unsigned> u(0,9);
    default_random_engine e(time(0));
    for(size_t i=0;i<10;++i)
        cout<<u(e)<<" ";
    cout<<endl;
    for(size_t i=0;i<10;++i)
        cout<<u(e)<<" ";
    cout<<endl;
}