rand()是否在OSX上返回零? [英] Does rand() ever return zero on OSX?

问题描述

我已经在没有爱的情况下运行了将近十个小时的代码:

I have been running this code for almost ten hours with no love:

 while ( true ) {
     int r = rand();
     assert( r != 0 );
 }

我希望rand()最终会变成零，从而触发断言.

I expect rand() to eventually roll a zero and thus trigger the assert.

我是在做错什么还是rand()永远不会返回零?

Am I doing something wrong or does rand() never return zero?

还是我没有等很久才期待看到它?我使用的是2012年老式2GHz i7.

Or have I not been waiting long enough to expect to see it? I'm on 2012-vintage 2GHz i7.

推荐答案

如果

If this link is the definition of Mac OS X rand(), then 0 will never be produced. It's not a very good pseudo random number generator, IMHO.

除其他缺陷外，它的状态是先前返回的值，这意味着它是从上一个值到下一个值的严格函数；它的周期不能大于其范围，即[1, RAND_MAX-1]. (它不能产生0，因为0在算法中是一个定点.)

Amongst its other flaws, its state is the previously returned value, which means that it is a strict function from previous value to next value; it's cycle cannot be larger than its range, which is [1, RAND_MAX-1]. (It cannot produce 0 because 0 is a fixed-point in the algorithm.)

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