所以,我一直对这个很着迷.
So, I've been nuts on this.
rand() % 6 将始终产生 0-5 之间的结果.
rand() % 6 will always produce a result between 0-5.
但是,当我需要介于两者之间时,可以说是 6-12.
However when I need between, let's say 6-12.
我应该有 rand() % 6 + 6
Should I have rand() % 6 + 6
0+6 = 6.
1+6 = 7.
...
5+6 = 11. ???
如果我想要间隔 6-12,那么我需要 +7 吗?但是,0+7 = 7.什么时候会随机6个?
So do I need to + 7 If I want the interval 6-12? But then, 0+7 =7. When will it randomize 6?
我在这里错过了什么?哪个是在 6 到 12 之间随机数的正确方法?为什么?我好像在这里遗漏了什么.
What am I missing here? Which one is the correct way to have a randomized number between 6 and 12? And why? It seems like I am missing something here.
如果 C++11 是一个选项,那么您应该使用 随机标头 和 uniform_int_distrubution.正如 James 在评论中指出的那样,使用 rand 和 %
有很多问题,包括偏差分布:
If C++11 is an option then you should use the random header and uniform_int_distrubution. As James pointed out in the comments using rand and %
has a lot of issues including a biased distribution:
#include <iostream>
#include <random>
int main()
{
std::random_device rd;
std::mt19937 e2(rd());
std::uniform_int_distribution<int> dist(6, 12);
for (int n = 0; n < 10; ++n) {
std::cout << dist(e2) << ", " ;
}
std::cout << std::endl ;
}
如果您必须使用 rand 那么应该这样做:
if you have to use rand then this should do:
rand() % 7 + 6
更新
使用 rand
的更好方法如下:
A better method using rand
would be as follows:
6 + rand() / (RAND_MAX / (12 - 6 + 1) + 1)
我从 C 常见问题解答 中获得了这个,并解释了 如何我得到一定范围内的随机整数? 问题.
I obtained this from the C FAQ and it is explained How can I get random integers in a certain range? question.
更新 2
Boost 也是一种选择:
#include <iostream>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int_distribution.hpp>
int main()
{
boost::random::mt19937 gen;
boost::random::uniform_int_distribution<> dist(6, 12);
for (int n = 0; n < 10; ++n) {
std::cout << dist(gen) << ", ";
}
std::cout << std::endl ;
}
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