std :: default_random_engine生成介于0.0和1.0之间的值 [英] std::default_random_engine generate values between 0.0 and 1.0

问题描述

我希望能够生成0.0到1.0之间的随机值

I want to be able to generate random values between 0.0 and 1.0

我尝试使用

std::default_random_engine generator;
std::uniform_real_distribution<float> distribution(0.0, 1.0);

float myrand = distribution(generator);

在循环中生成随机值始终为我提供以下值：

Generating random value in a loop gives me always these values:

0.000022

0.085032

0.601353

0.891611

0.967956

0.189690

0.514976

0.398008

0.262906

0.743512

0.089548

我该怎么做才能真正获得随机值？
如果我总是得到相同的东西，似乎不是那么随机。

What can I do to really get random values? Doesn't seem that random if I always get the same ones.

推荐答案

// 1-st variant: using time() function for seed random distribution
std::default_random_engine generator(time(0));
std::uniform_real_distribution<double> distribution(first, last);
return distribution(generator);

如果打开多个程序，并且使用相同的随机数生成器，它们将全部输出相同的结果，因为它们具有与时间相同的种子值。

If open multiple programs, with the same random number generator they will all output the same results, because they have the same value of seed which is time.

此问题通过使用随机设备在以下代码中解决：

This issue solved by using random device, in the below code:

// 2-nd variant: 
std::uniform_real_distribution<double> distribution(first, last);
std::random_device rd;
std::default_random_engine generator(rd());
return distribution(generator);

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