C# List internals

Question

What exactly happens when adding an object to a collection such as List?

List people = new List();
Person dan = new Person() { Na         


        

Answer 1

It's important in .NET programming to have a good understanding of the difference between reference types and value types. This article provides a good overview: http://www.albahari.com/valuevsreftypes.aspx

In this case, you created two Person objects (Daniel, age 10, and hw, age 44). It's the variables that reference the two objects that created the confusion.

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Person dan = new Person() { Name="daniel", Age=10 };

Here, a local variable, dan, is assigned a reference to the newly created (Daniel, age 10) object.

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people.Add(dan);

Here, the property people[0] is (indirectly via the List.Add method) assigned a reference to the existing (Daniel, age 10) object.

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dan = new Person() { Name = "hw", Age = 44 };

Here, the local variable, dan, is assigned a reference to the newly created (hw, age 44) object. But the property people[0] still holds a reference to the existing (Daniel, age 10) object.