.NET Parameter passing - by reference v/s by value

Question

I\'m trying to validate my understanding of how C#/.NET/CLR treats value types and reference types. I\'ve read so many contradicting explanations I stil

This is what

Answer 1

The term "pass by value" is a little misleading.

There are two things you are doing:

1) passing a reference type (Person p) as a parameter to a method

2) setting a refence type variable (Person p2) to an already existing variable (Person p)

Let's look at each case.

Case 1

You created Person p pointing to a location in memory, let's call this location x. When you go into method AppendWithUnderScore, you run the following code:

p.Name = p.Name + "_"; 

The method call creates a new local variable p, that points to the same location in memory: x. So, if you modify p inside your method, you will change the state of p.

However, inside this method, if you set p = null, then you will not null out the p outside the method. This behavior is called "pass by value"

Case 2

This case is similar to the above case, but slightly different. When you create a new variable p2 = p, you are simply saying that p2 references the object at the location of p. So now if you modify p2, you are modifying p since they reference the same object. If you now say p2 = null, then p will now also be null. Note the difference between this behavior and the behavior inside the method call. That behavioral difference outlines how "pass by value" works when calling methods