Value type and reference type problem

Question

Hi I\'m trying to do a simple swap of two objects.My code is

void Main()
{
  object First = 5;
  object Second = 10;

  Swap(First, Second);
  //If I display res         


        

Answer 1

You're passing the reference to the objects by value (pass by value is the default in C#).

Instead, you need to pass the objects to the function by reference (using the ref keyword).

private static void Swap(ref object first, ref object second)
{
    object temp = first;
    first = second;
    second = temp;
}

void Main()
{
    object first = 5;
    object second = 10;

    Swap(ref first, ref second);
}

Of course, if you're using C# 2.0 or later, you would do better to define a generic version of this function that can accept parameters of any type, rather than the object type. For example:

private static void Swap(ref T first, ref T second)
{
    T temp;
    temp = first;
    first = second;
    second = temp;
}

Then you could also declare the variables with their proper type, int.