[c#] Calculating the distance between 2 points

I have two points (x1,y1) and (x2,y2). I want to know whether the points are within 5 meters of one another.

Something like this in c# would probably do the job. Just make sure you are passing consistent units (If one point is in meters, make sure the second is also in meters)

private static double GetDistance(double x1, double y1, double x2, double y2)
{
   return Math.Sqrt(Math.Pow((x2 - x1), 2) + Math.Pow((y2 - y1), 2));
}

Called like so:

double distance = GetDistance(x1, y1, x2, y2)
if(distance <= 5)
{
   //Do stuff
}

If you are using System.Windows.Point data type to represent a point, you can use

// assuming p1 and p2 data types
Point p1, p2;
// distanc can be calculated as follows
double distance = Point.Subtract(p2, p1).Length;

Update 2017-01-08:

• Add reference to Microsoft documentation
• Result of Point.Subtract is System.Windows.Vector and it has also property LengthSquared to save one sqrt calculation if you just need to compare distance.
• Adding reference to WindowsBase assembly may be needed in your project
• You can also use operators

Example with LengthSquared and operators

// assuming p1 and p2 data types
Point p1, p2;
// distanc can be calculated as follows
double distanceSquared = (p2 - p1).LengthSquared;

Given points (X1,Y1) and (X2,Y2) then:

dX = X1 - X2;
dY = Y1 - Y2;

if (dX*dX + dY*dY > (5*5))
{
    //your code
}

You can use the below formula to find the distance between the 2 points:

distance*distance = ((x2 - x1)*(x2 - x1)) + ((y2 - y1)*(y2 - y1))

the algorithm : ((x1 - x2) ^ 2 + (y1 - y2) ^ 2) < 25

Here is my 2 cents:

double dX = x1 - x2;
double dY = y1 - y2;
double multi = dX * dX + dY * dY;
double rad = Math.Round(Math.Sqrt(multi), 3, MidpointRounding.AwayFromZero);

x1, y1 is the first coordinate and x2, y2 the second. The last line is the square root with it rounded to 3 decimal places.