the distance from a point to a line

Question

Write a function to calculate the distance from a point to a line. The formula describing the line is: Ax + By + C = 0. If the coordinates of the point P are ( 0 x , 0 y ), the distance d from the point P to the line can be calculated by:

(the rar file)

The function calculates and returns the distance from (x0, y0) to the line described by coefficients A, B and C.

Example:
The distance from (-2, 1.5) to the line described by 2x + 3.5y - 4 = 0 is found by:
dist = distance(2, 3.5, -4, -2, 1.5);

Vulpes · Answer

This should do it though there's no error checking (if input is invalid 0 is substituted): using System; class Program { static void Main() { double A B C x y dist; Console.Write(Enter A : ); double.TryParse(Console.ReadLine() out A); Console.Write(Enter B : ); double.TryParse(Console.ReadLine() out B); Console.Write(Enter C: ); double.TryParse(Console.ReadLine() out C); Console.Write(Enter x : ); double.TryParse(Console.ReadLine() out x); Console.Write(Enter y : ); double.TryParse(Console.ReadLine() out y); dist = distance(A B C x y); Console.WriteLine(The distance between them is {0} dist); Console.ReadKey(); } static double distance(double A double B double C double x double y) { double num = Math.Abs(A * x + B * y + C); double denom = Math.Sqrt(A * A + B * B); return num/denom; } }