Using List.Sort()

Question

Hi,

How to use Sort function.
The run-time exception occurs when I use the function

 private void Button_Clicked(object sender, EventArgs e)  
    {  
        List<AbcData> parts = new List<AbcData>();  
        parts.Add(new AbcData() { letter = "B", number = 5 });  
        parts.Add(new AbcData() { letter = "C", number = 4 });  
        parts.Add(new AbcData() { letter = "A", number = 2 });  
        parts.Add(new AbcData() { letter = "E", number = 1 });  
        parts.Add(new AbcData() { letter = "D", number = 3 });  
  
        parts.Sort();  // System.InvalidOperationException: 'Failed to compare two elements in the array  
  
    }  

. . .

 public class AbcData  
    {  
        public int number { get; set; }  
        public string letter { get; set; }  
  
    }  

Answer 1

    private void Button_Clicked(object sender, EventArgs e)  
    {  
        List<AbcData> parts = new List<AbcData>( );  
        parts.Add( new AbcData( ) { letter = "B", number = 5 } );  
        parts.Add( new AbcData( ) { letter = "C", number = 4 } );  
        parts.Add( new AbcData( ) { letter = "A", number = 2 } );  
        parts.Add( new AbcData( ) { letter = "E", number = 1 } );  
        parts.Add( new AbcData( ) { letter = "D", number = 3 } );  

        parts.Sort( );  
    }  



public class AbcData : IComparable  
{  
     //you need to implement explicitly member of IComparable   
    public int CompareTo( object o )  
    {  
        AbcData o2 = (AbcData)o;  
        return number.CompareTo( o2.number );  
    }  
    public int number  
    {  
        get; set;  
    }  
    public string letter  
    {  
        get; set;  
    }  
}  

Answer 2

See samples in MSDN : List<T>.Sort Method
or from Google : How to sort a list in C#

Answer 3

The run-time exception occurs when I use the function

And which exception exactly do you get or do we have to guess?
You use a customer class and that one must implement IComparable<T> Interface to be sortable.