C++ 最小值和最大值之间的随机双倍
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/10776073/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Random double between min and max
提问by David Gomes
double get_random(double min, double max) {
/* Returns a random double between min and max */
return min * ((double) rand() / (double) RAND_MAX) - max;
}
That's my function to generate random doubles between a min and a max. However, when I call get_random(-1.0, 1.0);, I get values between -2.0 and -1.0.
这是我在最小值和最大值之间生成随机双打的功能。但是，当我调用 时get_random(-1.0, 1.0);，我得到的值介于 -2.0 和 -1.0 之间。
Any idea of what I'm doing wrong and how I can fix it?
知道我做错了什么以及如何解决吗？
回答by Luchian Grigore
Shouldn't the formula be
公式不应该是
(max - min) * ( (double)rand() / (double)RAND_MAX ) + min
(double)rand() / (double)RAND_MAXreturns a random number between0and1(max - min) * ( (double)rand() / (double)RAND_MAX )returns a random number between0andmax - min.- the whole expression will return a random number between
0 + minandmin + (max-min)- i.e.minandmax.
(double)rand() / (double)RAND_MAX返回一个介于0和之间的随机数1(max - min) * ( (double)rand() / (double)RAND_MAX )返回0和之间的随机数max - min。- 整个表达式将返回一个介于
0 + minand之间的随机数min + (max-min)- 即minandmax。
回答by user2514807
You can use this for generating random double or floating numbers:
您可以使用它来生成随机双精度或浮点数：
((double) rand()*(max-min)/(double)RAND_MAX-min);
