任意实数范围内的随机数生成原理图解

1 //产生[low,high]内的任意随机数,并返回
2 float randnum(float low,float high)
3 {
4 int ret_rnd = 0.0;
5
6 float integerf = 0.0;
7 float driftf = 0.0;
8
9 if (low >= high)
10 {
11 printf("low >= high,rearrange them\n");
12 getchar();
13 return;
14 }
15 //---------------------------------------------
16
17 int integer; //整数部分
18 int decimals; //小数部分
19
20 float diff = high - low;
21
22 integer = (int)(high - low); //取整数部分
23
24 decimals = diff - integer; //取小数部分
25 //---------------------------------------------
26
27 //1.先计算一个整数偏量值
28 if (integer > 0)
29
30 integerf= (float)(rand() % integer);
31
32 else
33 integerf= 0.0;
34
35 //2.在整数偏量的基础上进行波动
36 do
37 {
38 driftf = (float)(rand() / RAND_MAX);//产生小数
39
40 driftf *= (rand() % 2 == 0 ? 1 : -1);
41
42 } while ((integerf+driftf<0)||(integerf+driftf>diff));
43
44
45
46 ret_rnd = low+(integerf + driftf) ;
47
48 return ret_rnd;
49
50
51 }