Sort List alternative in c#

Question

I have a number of objects, all from the same class(ColorNum) Each object has 2 member variabels (m_Color and m_Number)

Example:

ColorNum1(Red,25)
ColorNum2(Blue,5)
ColorNum3(Red,11)
ColorNum4(White,25)

The 4 objects are in the ColorNumList

List<ColorNum> ColorNumList = new List<ColorNum>();

Now I want to order the list so the objects with mColor = "Red" is in the top. I dont care about the order of the remaining objects.

What should my predicate method look like?

Answer 1

Using linq:

var sortedRedAtTop = 
    from col in ColorNumList 
    order by col.Color == Red ? 1 : 2
    select col;

Or the list's sort method:

ColorNumList.Sort( (x,y) => 
    (x.Color == Red ? 1 : 2)-(y.Color == Red ? 1 : 2) );

Answer 2

ColorNumList.Sort((x, y) => x.m_Color == Red ? 1 : (y.m_Color == Red ? -1 : 0));

Answer 3

See http://msdn.microsoft.com/en-us/library/system.array.sort(VS.71).aspx

[C#] public static void Sort(Array, Array, int, int, IComparer);

You need to implement a function that compares two objects and returns a value indicating whether one is less than, equal to or greater than the other.

http://msdn.microsoft.com/en-us/library/system.collections.icomparer.compare(VS.71).aspx

You need to write a class that implemenets the IComparer interface.

I haven't been using C#, but here is the VB equivalent:

Class ColorCompare Implements IComparer

    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
        Dim xc As ColorNum = TryCast(x, ColorNum)
        Dim yc As ColorNum = TryCast(y, ColorNum)
        If x.color = Red Then
            Return 1
        ElseIf y.color = Red Then
            Return -1
        Else
            Return 0
        End If
    End Function
End Class