我看到了许多问题上的SO关于这个特定主题，但他们都没有给我任何答案，所以我想提出这个问题的。

I have seen many questions on SO about this particular subject but none of them has any answer for me, so I thought of asking this question.

我想生成之间的随机数[-1,1]。我怎样才能做到这一点？

I wanted to generate a random number between [-1, 1]. How I can do this?

推荐答案

使用 1 + 2 *（（浮点）兰特（））/ RAND_MAX

兰特（）生成整数范围内的 [0，RAND_MAX] 包容性，因此，（（浮点）兰特（））/ RAND_MAX 返回 [0,1] 。我们得到的随机数从 [ - 1,1] 将它添加到 1

rand() generates integers in the range [0,RAND_MAX] inclusive therefore, ((float)rand())/RAND_MAX returns a floating-point number in [0,1]. We get random numbers from [-1,1] by adding it to -1.

编辑：（添加注释部分的相关部分）

(adding relevant portions of the comment section)

在这种方法的局限性：

（（浮点）兰特（））/ RAND_MAX 返回一个百分比（从0分至1）。如此以来，介于-1到1的范围是2的整数，我乘以分数为2，然后将它添加到你想要的最低数目，-1。这也告诉你关于你的随机数的质量，因为你只会有 RAND_MAX 独特的随机数。

((float)rand())/RAND_MAX returns a percentage (a fraction from 0 to 1). So since the range between -1 to 1 is 2 integers, I multiply that fraction by 2 and then add it to the minimum number you want, -1. This also tells you about the quality of your random numbers since you will only have RAND_MAX unique random numbers.