第 16 章 C 预处理器和 C 库（直角坐标转换极坐标）

 1 /*-------------------------------------
 2     rect_pol.c -- 把直角坐标转换为极坐标
 3 -------------------------------------*/
 4 
 5 #include <stdio.h>
 6 #include <math.h>
 7 
 8 #define RAD_TO_DEG    (180 / (4 * atan(1.0)))
 9 
10 typedef struct polar_v
11 {
12     double magnitude;
13     double angle;
14 } Polar_V;
15 
16 typedef struct rect_v
17 {
18     double x;
19     double y;
20 } Rect_V;
21 
22 Polar_V rect_to_polar(Rect_V);
23 
24 int main()
25 {
26     Rect_V input;
27     Polar_V result;
28 
29     puts("Enter x and y coordinates; enter q to quit:");
30     while (scanf("%lf %lf", &input.x, &input.y) == 2)
31     {
32         result = rect_to_polar(input);
33         printf("magnitude = %0.2f, angle = %0.2f\n", result.magnitude, result.angle);
34     }
35     
36     return 0;
37 }
38 
39 Polar_V rect_to_polar(Rect_V rv)
40 {
41     Polar_V pv;
42 
43     pv.magnitude = sqrt(pow(rv.x, 2) + pow(rv.y, 2));
44     if (pv.magnitude == 0)
45         pv.angle = 0;
46     else
47         pv.angle = RAD_TO_DEG * atan2(rv.y, rv.x);
48 
49     return pv;
50 }

rect_pol.c