How Value Types and Reference Types Work in C#?

20 October, 2024

Value Type:

In C#, value types store data directly in memory. Common value types include int, float, bool, and structs. When you assign one value type to another, a copy of the value is made, meaning each variable holds its own data.

Value types copy data during assignment.
Changes to one variable do not affect the other.
Stored in stack memory, which makes access faster.

Reference Type:

In C#, reference types store a reference (or memory address) to the actual data, not the data itself. Common reference types include classes, arrays, and strings. When you assign one reference type variable to another, both variables point to the same memory location.

Student st1 = new Student();
Here, = is the assignment operator. By st1, we create a reference type variable that will hold a value.

By new Student(), memory is allocated for a new Student object. Initially, the values in this memory will be null or 0.

Then, st1 holds the reference to this object, meaning st1 is pointing to or linking the object.

Now, what does st1 = st2 mean?

It means that now both st1 and st2 will point to the same object. When the line st1 = st2 is executed, st1 will point to the same object that st2 is pointing to. And the object that st1 was previously pointing to will become orphaned, as it no longer has a reference, and it will be garbage collected.

Therefore, the object now has two references (st1 and st2).

Remember, this is not copying. The values are not being copied. Now, if st2 is set to null, st2’s reference will become null, but st1 will not change. So, this is not copying; this is passing a reference.

Summary:

If an object has no reference, it becomes an orphan object.

Multiple references can point to the same object.

A reference can point to one object at a time or remain unreferenced, not pointing to any object.

This is how reference types work.

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