Use of 'ref' keyword in C# [duplicate]

Answer 1

Using ref means that the reference is passed to the function.

The default behaviour is that the function receives a new reference to the same object. This means if you change the value of the reference (e.g. set it to a new object) then you are no longer pointing to the original, source object. When you pass using ref then changing the value of the reference changes the source reference - because they are the same thing.

Consider this:

public class Thing
{
    public string Property {get;set;}
}

public static void Go(Thing thing)
{
    thing = new Thing();
    thing.Property = "Changed";
}

public static void Go(ref Thing thing)
{
    thing = new Thing();
    thing.Property = "Changed";
}

Then if you run

var g = new Thing();

// this will not alter g
Go(g);

// this *will* alter g
Go(ref g);