Why should I use a private variable in a property accessor?

Question

Sorry If I am being noob, I have this doubt, why do we use private variables and set them using properties ?

Why can't we just use properites alone ?

I am talking about situations like this

private string _testVariable;  public string MyProperty {     get { return _testVariable;}     set {_testVariable = value;} } 

I am thinking of simply using

public string MyProperty { get; set; }  

Why redundant private variable? are these two strategies different ? can anyone please throw some light on this.

Thanks

Answer 1

Your examples are semantically the same. The concise property declaration syntax (just having { get; set; }) is a shortcut available in C# 3.0. The compiler actually creates a private backing variable and a simple getter and setter as in your first example.

If all you're doing is creating a getter and setter (and nothing actually happens when either occurs), then the concise syntax is a good option. If you have to perform any other actions (redraw a control, for example) when you set the value, then the full syntax is required.

Answer 2

Why redundant private variable? are these two strategies different ? can anyone please throw some light on this.

If all your doing is reading/writing a variable, then no. Otherwise, there's two reasons why you'd want a private variable:

Data validation

// Data validation public class IntWrapper {     private int _value;     public int Value     {         get { return _value; }         set         {             if (value < 0) { throw new Exception("Value must be >= 0"); }             _value = value;         }     } } 

Getter/setter wraps up an underlying data store

public class StringBuffer {     List<char> chars = new List<char>();      // Wraps up an underlying data store     public string Value     {         get { return new String(chars.ToArray()); }         set { chars = new List<char>(value.ToCharArray()); }     }      public void Write(string s) { Write(chars.Count, s); }      public void Write(int index, string s)     {         if (index > chars.Count) { throw new Exception("Out of Range"); }         foreach(char c in s)         {             if (index < chars.Count) { chars[index] = c; }             else { chars.Add(c); }             index++;         }     } }