Output parameters in C#

Output parameter is very interesting concept about passing parameters in C#, basically output parameters are used to pass result back to the calling method.For it we use out keyword. Output parameter does not create a new storage location similar to reference parameters.
It is necessary to use out keyword to declare parameter when corresponding actual parameters declared as out.

In the following example we pass the i integer type value as out parameter that has no value. after calling GetNumber() method, value of i get change to 5.

class Shape
{  
     public void main()
    {
        int i;
        GetNumber(out i);
        Console.WriteLine(i);
    }
    public void GetNumber(out int x)
    {
        x = 5;
    }   
}