ColumnSort.cs

using System.Collections;
using System.Windows.Forms;

/// <summary>
/// This class is an implementation of the 'IComparer' interface.
/// </summary>
public class ListViewColumnSorter : IComparer
{

    /// <summary>
    /// Case insensitive comparer object
    /// </summary>
    private readonly CaseInsensitiveComparer ObjectCompare;

    /// <summary>
    /// Class constructor. Initializes various elements
    /// </summary>
    public ListViewColumnSorter()
    {
        // Initialize the column to '0'
        SortColumn = 0;

        // Initialize the sort order to 'none'
        Order = SortOrder.Ascending;

        // Initialize the CaseInsensitiveComparer object
        ObjectCompare = new CaseInsensitiveComparer();
    }

    /// <summary>
    /// This method is inherited from the IComparer interface. It compares the two objects passed using a case insensitive comparison.
    /// </summary>
    /// <param name="x">First object to be compared</param>
    /// <param name="y">Second object to be compared</param>
    /// <returns>The result of the comparison. "0" if equal, negative if 'x' is less than 'y' and positive if 'x' is greater than 'y'</returns>
    public int Compare(object x, object y)
    {
        int compareResult;
        ListViewItem listviewX, listviewY;

        // Cast the objects to be compared to ListViewItem objects
        listviewX = (ListViewItem)x;
        listviewY = (ListViewItem)y;
        if (SortColumn == 5)
        {
            try
            {
                int yNum = int.Parse(cleanNumber(listviewY.SubItems[SortColumn].Text));
                int xNum = int.Parse(cleanNumber(listviewX.SubItems[SortColumn].Text));
                return xNum == yNum ? 0 : xNum > yNum && Order == SortOrder.Ascending ? -1 : 1;
            }
            catch { }
        }

        // Compare the two items
        compareResult = ObjectCompare.Compare(listviewX.SubItems[SortColumn].Text, listviewY.SubItems[SortColumn].Text);

        // Calculate correct return value based on object comparison
        if (Order == SortOrder.Ascending)
        {
            // Ascending sort is selected, return normal result of compare operation
            return compareResult;
        }
        else if (Order == SortOrder.Descending)
        {
            // Descending sort is selected, return negative result of compare operation
            return -compareResult;
        }
        else
        {
            // Return '0' to indicate they are equal
            return 0;
        }
    }

    /// <summary>
    /// Gets or sets the number of the column to which to apply the sorting operation (Defaults to '0').
    /// </summary>
    public int SortColumn { set; get; }

    /// <summary>
    /// Gets or sets the order of sorting to apply (for example, 'Ascending' or 'Descending').
    /// </summary>
    public SortOrder Order { set; get; }

    private string cleanNumber(string number)
    {
        return number.Substring(0);
    }

}