How to measure how long IComparer took?

Question

Hi I'm currently writing a testing plan for part of my project and I would like to know how to measure how long my sort function takes. My attempt looked like this:

    private void byIGNameToolStripMenuItem_Click(object sender, EventArgs e)
    {
        GameDB.Sort(new PlayerNameComparer());
        currentEntryShown = 0;
        ShowData();
        UpdatePrevNextBtnStatus();
    }
    public class PlayerNameComparer : IComparer
    {
        Stopwatch stopwatch = new Stopwatch();
        stopwatch.Start();
        public int Compare(object x, object y)
        {
            return ((Player)x).playerIgName.CompareTo(((Player)y).playerIgName);
        }
        stopwatch.Stop();
        MessageBox.Show("Time Elapsed:" + stopwatch.ElapsedMilliseconds);
    }

But I get a compiler error: 'DBProject.Form1.PlayerNameComparer.stopwatch' is a 'field' but is used like a 'type'

Answer 1

You are executing statements in the class area, not in the method ; )
In PL language -> Nie mozesz wykonywać kodu w obrębie klasy, rób to w metodach : )
Just put them into the method

public int Compare(object x, object y)
{
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
int ret =((Player)x).playerIgName.CompareTo(((Player)y).playerIgName)
stopwatch.Stop();
MessageBox.Show("Time Elapsed:" + stopwatch.ElapsedMilliseconds); 
    return ret;

}

but that code executes for every item you want to sort, so its better if you start your watch before sorting, and stop after like this: )

private void byIGNameToolStripMenuItem_Click(object sender, EventArgs e)
{    
    Stopwatch stopwatch = new Stopwatch();
    stopwatch.Start();
    GameDB.Sort(new PlayerNameComparer());
    stopwatch.Stop();
    MessageBox.Show("Time Elapsed:" + stopwatch.ElapsedMilliseconds); 

    currentEntryShown = 0;
    ShowData();
    UpdatePrevNextBtnStatus();
}
public class PlayerNameComparer : IComparer
{
    public int Compare(object x, object y)
    {
        return ((Player)x).playerIgName.CompareTo(((Player)y).playerIgName);
    }
}

Answer 2

That answer is totally wrong as you are in the Compare method and that gets called multiple times during sorting.

A way to test this would be something similar to this:

private void byIGNameToolStripMenuItem_Click(object sender, EventArgs e)
{
    Stopwatch stopwatch = new Stopwatch();
    stopwatch.Start();

    GameDB.Sort(new PlayerNameComparer());

    stopwatch.Stop();
    MessageBox.Show("Time Elapsed:" + stopwatch.ElapsedMilliseconds);

    currentEntryShown = 0;
    ShowData();
    UpdatePrevNextBtnStatus();
}
public class PlayerNameComparer : IComparer
{

    public int Compare(object x, object y)
    {
        return ((Player)x).playerIgName.CompareTo(((Player)y).playerIgName);
    }

}

Also consider using the generic version of the IComparer since its strongly typed and you do not need to unbox from an object type to your class type.

A good example could be:

public class StringComparer : IComparer<string>
{
    public int Compare(string x, string y)
    {
        return x.CompareTo(y);
    }
}

which in your case could transform into:

public class PlayerNameComparer : IComparer<Player>
{
    public int Compare(Player x, Player y)
    {
        return x.playerIgName.CompareTo(y.playerIgName);
    }
}