rect_pol.c

c primer plus 第五版 的源代码

/* rect_pol.c -- converts rectangular coordinates to polar */
#include <stdio.h>
#include <math.h>

#define RAD_TO_DEG (180/(4 * atan(1)))

typedef struct polar_v {
    double magnitude;
    double angle;
} POLAR_V;

typedef struct rect_v {
    double x;
    double y;
} RECT_V;

POLAR_V rect_to_polar(RECT_V);

int main(void)
{
    RECT_V input;
    POLAR_V result;

    puts("Enter x,y coordinates; enter q to quit:");
    while (scanf("%lf %lf", &input.x, &input.y) == 2)
    {
        result = rect_to_polar(input);
        printf("magnitude = %0.2f, angle = %0.2f\n",
                result.magnitude, result.angle);
    }
    puts("Bye.");
    
    return 0;
}

POLAR_V rect_to_polar(RECT_V rv)
{
    POLAR_V pv;

    pv.magnitude = sqrt(rv.x * rv.x + rv.y * rv.y);
    if (pv.magnitude == 0)
        pv.angle = 0.0;
    else
        pv.angle = RAD_TO_DEG * atan2(rv.y, rv.x);
    
    return pv;
}