Question

我想在for循环中生成三个随机数：

for (i=0; i<100; i++)
{
  item1 = rand()/(double)RAND_MAX*100;
  item2 = rand()/(double)RAND_MAX*200;
  item3 = rand()/(double)RAND_MAX*300;
}

所以我的问题是：

如何为每个项目1,2和3获得等间隔的随机数

如item1 = 10,20,30,40,50 item2 = 40,60,80，item3 = 25,35,45等。

Answer 1

你想要的数字根本不是随机的，这就是序列

您可以执行类似

的操作

int sequence =5;
int initial=10;

For (i=0; i<100; i++)
{
item1 = initial;
initial=initial+sequence;
item2 = initial;
initial=initial+sequence;
item3 = initial;
initial=initial+sequence;
}

它将生成10,15,20 ......

Answer 2

您只想对随机数进行舍入，或者在生成后缩放/投影它们。

这是...乘法。示例：（ Live On Coliru ）

#include <random>
#include <iostream>

int main()
{
    std::mt19937 engine(time(NULL));
    std::uniform_int_distribution<int> dist(0,10); // arbitrary range chosen

    for (int i=30; i>0; --i)
    {
        int random = dist(engine);
        std::cout << (random*10) << "\t" << (random*20) << "\t" << (random*10 + 15) << "\n";
    }
}

输出：

90  180 105
30  60  45
90  180 105
50  100 65
70  140 85
10  20  25
40  80  55
30  60  45
80  160 95
60  120 75
0   0   15
40  80  55
20  40  35
20  40  35
90  180 105
50  100 65
80  160 95
0   0   15
0   0   15
0   0   15
40  80  55
50  100 65
10  20  25
60  120 75
100 200 115
80  160 95
70  140 85
90  180 105
30  60  45
60  120 75

Answer 3

也许您正在尝试获取随机等间隔序列的初始随机数，如下所示：

for (i=0; i<100; i++)
{
    if(i == 0)
    {
        item1 = rand()/(double)RAND_MAX*100;
        item2 = rand()/(double)RAND_MAX*200;
        item3 = rand()/(double)RAND_MAX*300;

        increment1 = rand()/(double)RAND_MAX*100;
        increment2 = rand()/(double)RAND_MAX*200;
        increment3 = rand()/(double)RAND_MAX*300;
    }
    else
    {
        item1 += increment1;
        item2 += increment2;
        item3 += increment3;
    }

    //do stuff
}

如何获得均匀分布的随机数？

3 个答案: