如何生成一个大于RAND_MAX的随机整数 [英] How to generate a random integer that is bigger than RAND_MAX

问题描述

如何生成一个大于RAND_MAX的随机整数。

RAND_MAX是rand函数的最大值。等于0x7fff

How to generate a random integer that is bigger than RAND_MAX.
the RAND_MAX is the max of rand function. and equal to 0x7fff

推荐答案

？μ·é£？写道：

如何生成一个大于RAND_MAX的随机整数。
RAND_MAX是rand函数的最大值。等于0x7fff

How to generate a random integer that is bigger than RAND_MAX.
the RAND_MAX is the max of rand function. and equal to 0x7fff

这是一个实施质量问题。我使用的实现是使用RAND_MAX等于0x7fffffff。


无论如何你可以使用提升随机库，顺便说一句

接受C ++ 0x标准草案。

This is a quality of implementation issue. The implementation I am
using has RAND_MAX equal to 0x7fffffff.

Anyway you can use the boost random library which was by the way
accepted into the draft C++0x standard.

？μ·é£？写道：

如何生成一个大于RAND_MAX的随机整数。
RAND_MAX是rand函数的最大值。等于0x7fff

How to generate a random integer that is bigger than RAND_MAX.
the RAND_MAX is the max of rand function. and equal to 0x7fff

如果RAND_MAX = 0x7fff ...则可以使用：


unsigned int r = ~rand （）;


如果（我认为很常见）RAND_MAX是最大的[signed] int（例如，16位的
0x7fff，32位的0x7fffffff） ，然后你得到一个随机数

从RAND_MAX + 1到2 * RAND_MAX - 1（0x8000 ......到0xffff ...）包含。


证明留给读者作为练习。 :)


HTH，


斯图尔特

If RAND_MAX = 0x7fff... then you can use:

unsigned int r = ~rand();

If (as I believe is common) RAND_MAX is the largest [signed] int (e.g.
0x7fff in 16bit, 0x7fffffff in 32 bit), then you get a random number
from RAND_MAX + 1 to 2 * RAND_MAX - 1 (0x8000... to 0xffff...) inclusive.

Proof left as an exercise to the reader. :)

HTH,

Stewart

" ??"写道：

"??" wrote:

如何生成一个大于RAND_MAX的随机整数。
RAND_MAX是rand函数的最大值。并且等于0x7fff

How to generate a random integer that is bigger than RAND_MAX.
the RAND_MAX is the max of rand function. and equal to 0x7fff

使用移位运算符并将两个（或更多）调用的结果添加到rand（）

到更大的类型。 rand（）返回随机*位*的集合。

Use a shift operator and add the result of two (or more) calls on rand()
into a larger type. rand() returns a collection of random *bits*.

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