Should I use public properties and private fields or public fields for data?

Question

In much of the code I have seen (on SO, thecodeproject.com and I tend to do this in my own code), I have seen public properties being created for every single private field that a class contains, even if they are the most basic type of get; set; like:

private int myInt; public int MyInt  {      get { return myInt; }      set { myInt = value } } 

My question is: how does this differ from:

public int MyInt; 

and if we should use properties instead of public fields why should we use them in this specific case? (I am not talking about more complex examples where the getters and setters actually do something special or there is only one get or set (read/write only) rather than just returning/setting a value of a private field). It does not seem to add any extra encapsulation, only give a nice icon in IntelliSense and be placed in a special section in class diagrams!

Answer 1

See this article http://blog.codinghorror.com/properties-vs-public-variables/

Specifically

• Reflection works differently on variables vs. properties, so if you rely on reflection, it's easier to use all properties.
• You can't databind against a variable.
• Changing a variable to a property is a breaking change.

Answer 2

Three reasons:

1. You cannot override fields in subclasses like you can properties.
2. You may eventually need a more complex getter or setter, but if it's a field, changing it would break the API.
3. Convention. That's just the way it's done.

I'm sure there are more reasons that I'm just not thinking of.

In .Net 3.x you can use automatic properties like this:

public int Age { get; set; } 

instead of the old school way with declaring your private fields yourself like this:

private int age;  public int Age {     get { return age; }     set { age = value; } } 

This makes it as simple as creating a field, but without the breaking change issue (among other things).