Difference between Automatic Properties and public field in C# 3.0

Question

I failed to understand why auto implemented property language feature exist in C# 3.0.

What the difference it is making when you say

public string FirstName;

than

public string FirstName { get; set; }

Answer 1

Because they are implemented differently in the resulting IL code (and machine language). An Automatic property is still exposed as a public getter and setter, whereas a public field is just that - a single field..

Thus, implementing an auto property allows you at some later date to change the internal behavior of either the getter or setter (like adding a validator) without recompiling or re=coding any dependant classes that use it...

Answer 2

Just to add to what other people have said, declaring a public field, the field is accessible for read and write. declaring public automatic property, although the property is public, you can still add modifier to control the accessibility at the get/set level.

public string FirstName { get; private set; }

The user of your class sees FirstName as public property. However, he/she cannot write to it.