Class objects can also be stored in Arrays, Dictionaries and Lists just like structs however it is important to note that class objects are passed by reference while struct objects are passed by value.

This concept is important because passing simple values like int, float or double into methods is different from passing complex objects and structures into methods. Let's look at an example to understand this concept better.

We will create a simple struct object and pass it into a method. We will change its value from inside the method and see what happens to the value of the original object:

The output shows that the value of passedObject was updated while the value of originalObject remained unchanged. This shows that when we pass a struct object into a method, a duplicate of that object is created and passed into the method, or in other words, it is passed by value.

Now let's use the exact same code, only changing the term struct to class:

You'll notice that the output has changed - both the passedObject and the originalObject have the same value this time. This proves that when we pass a class object into a method, it passes a reference to the original object into the method, making changes to passedObject changes originalObject.

This property also applies when assigning objects to variables. Following is an example that shows the behavior of a struct object:

The same code but this time for a class object: