TheAlgorithms-C/misc/cartesian_to_polar.c

#include <math.h>
#include <stdio.h>

const double pi = 3.141592653589793238462643383279502884;

/**
give as arguments to the executable two x and y coordinates
outputs a polar coordinate
*/
int main()
{
    double x, y;
    double r, theta, thetaFinal;
    scanf("%lf %lf", &x, &y);
    r = hypot(x, y);
    if (x != 0)
    {
        if (y != 0)
        {
            theta = atan(y / x);
            if ((x > 0 && y > 0) || (x == -y))
            {  // Q1
                thetaFinal = theta;
            }
            else if (x < 0 && y > 0)
            {  // Q2
                thetaFinal = theta + pi;
            }
            else if (x < 0 && y < 0)
            {  // Q3
                thetaFinal = theta - pi;
            }
            else if (x > 0 && y < 0)
            {  // Q4
                thetaFinal = 2 * pi - theta;
            }
        }
    }
    if (x == 0)
    {  // exceptions when no actual angle is present
        if (y > 0)
        {
            thetaFinal = pi / 2;
        }
        else
        {
            thetaFinal = -(pi / 2);
        }
    }
    if (y == 0)
    {
        if (x > 0)
        {
            thetaFinal = 0;
        }
        else
        {
            thetaFinal = -pi;
        }
    }
    printf("%.2f %.2f\n", r, atan2(y, x));
}