C ++ 0x中的随机数 [英] Random numbers in C++0x

问题描述

新的C ++ 11标准有一整章专门用于随机数生成器。但是我如何执行最简单，最常见的任务，过去这样编码，但不求助于标准的C库：

 srand int）time（0））; 
 int i = rand（）; 

有合理的默认值为随机数引擎，分布和种子，可以使用

b p $ p> std :: default_random_engine e（（unsigned int）time（0））;
int i = e（）;


default_random_engine 的质量取决于实现。您也可以使用 std :: min_rand0 或 std :: min_rand 。

可能一个更好的种子随机引擎的方法是使用实​​现中的随机数，而不是使用 time 。

Eg

  std :: random_device rd; 
 std :: default_random_engine e（rd（））; 
  

The new C++11 Standard has a whole chapter dedicated to random number generators. But how do I perform the simplest, most common task that used to be coded like this, but without resorting to the standard C library:

srand((unsigned int)time(0));
int i = rand();

Are there reasonable defaults for random-number engines, distributions, and seeds that one could use out of the box?

解决方案

You should be able to do something like:

std::default_random_engine e((unsigned int)time(0));
int i = e();

The quality of the default_random_engine is implementation dependent. You could also use std::min_rand0 or std::min_rand.

Probably a better way to seed a random engine is with as true a random number as is available from the implementation rather than use time.

E.g.

std::random_device rd;
std::default_random_engine e( rd() );

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