Cell Subtraction in DataGridView

[BleepyEvans]

Hey,

Im wondering how can I subtract a value from the value in the previous cell or cell above. Please read everything as its much harder than I just made out

-

I have created a stopwatch, and previous to using a datagridview, ive been using labels with this code:

If LapTimeLabel1.Text = "0:0.000" Then
            LapTimeLabel1.Text = StopwatchLabel.Text
            lapTime = DateTime.Now()
        ElseIf LapTimeLabel2.Text = "0:0.000" Then
            Dim span As TimeSpan = DateTime.Now.Subtract(lapTime)
            LapTimeLabel2.Text = span.Minutes.ToString & ":" & span.Seconds.ToString & "." & span.Milliseconds
            lapTime = DateTime.Now()
            .......

It basically subjects the time captured on the previous button click and subtracts it from the current time. This will create the Lap time. With a datagrid this method is now not possible.

-

With help from you guys on here, Ive made a data grid which adds a new row on a button click, on the same button click it shows the lap number, the Split time, and hopefully in the end, the Lap Time.

This is my semi working code:

Private Sub LapButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LapButton.Click

        Dim lapTime As String
        Dim PreviouslapTime As DateTime

        i += 1
        DataGridView1.Rows.Add(i, StopwatchLabel.Text, lapTime)

        PreviousLapTime = DateTime.Now()
        Dim span As TimeSpan = DateTime.Now.Subtract(PreviouslapTime)
        lapTime = span.Minutes.ToString & ":" & span.Seconds.ToString & "." & span.Milliseconds

        Label3.Text = Label3.Text + Val(1)
    End Sub

Label 3 is my lap count which you can just ignore.

The problem with this code is that its basically just subtracting the time now and the time now, which is 0:0.0.

-

This is where I was thinking about just simply subtracting the previous cell from the current time, to get my new lap time, but you cant subtract strings.

-

If anyone has any other ideas then please post them, even if your not sure if it will work as im out of ideas.

Thanks

 

[mjwest10]

You want to use DateTime.Parse to convert the string value of the cell into a DateTime. Then you can subtract them like you want. See DateTime.Parse and TryParse example on this page.

 

[BleepyEvans]

Looks promising.

How would I choose the cell directly above the one I am wanting to subtract. In my case 1 row above, column 3?

 

[mjwest10]

I don't have VB.NET in front of me right now but off the top of my head I think you would do something like this (Before you increment i):

Dim prevValue as String = DataGridView1.Rows.Cells[3].Value.ToString()
PreviouslapTime = DateTime.Parse(prevValue)

...

Note: Rows and Cells are 0 based so the code above will grab the 4th cell not the third. If you want the third use 2 instead.

Also: If this is helpful please "Like" it. Thanks!

 

[BleepyEvans]

When I paste that code in, I do get errors

Errors:

You can ignore Error 1


New Code:

Private Sub LapButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LapButton.Click
        Dim prevValue as String = DataGridView1.Rows[i].Cells[3].Value.ToString()
        PreviouslapTime = DateTime.Parse(prevValue)

        i += 1
        DataGridView1.Rows.Add(i, StopwatchLabel.Text, lapTime)

        PreviouslapTime = DateTime.Now()
        Dim span As TimeSpan = DateTime.Now.Subtract(PreviouslapTime)
        lapTime = span.Minutes.ToString & ":" & span.Seconds.ToString & "." & span.Milliseconds

        Label3.Text = Label3.Text + Val(1)
    End Sub

---

I was having a play around and not even this was working

datagridview1.rows[1].Cells[0].Value

It wants an Identifier

 

[mjwest10]

Sorry about that I mixed C# and VB.NET code. I think if you change the square brackets to ( ) on the indexes it should work.

Its probably also a capital on Rows. Type it in yourself and use the intelli-sense to make sure.

 

[BleepyEvans]

Your right, () solved the errors going to try it now.

Also that means that MSDN is wrong:
DataGridView.Rows Property (System.Windows.Forms)

 

[BleepyEvans]

Unfortunatly that doesnt work, I believe it could be due to the fact that its trying to get the row before hand before its had chance to add a row.

But even after using an If statement, it still doesnt work.

Any ideas?

----

Heres the error I get:


Code:

Private Sub LapButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LapButton.Click
        If DataGridView1.Rows.Count > 0 Then
            Dim prevValue As String = DataGridView1.Rows(i).Cells(3).Value.ToString()
            PreviouslapTime = DateTime.Parse(prevValue)
            i += 1
            Dim span As TimeSpan = DateTime.Now.Subtract(PreviouslapTime)
            lapTime = span.Minutes.ToString & ":" & span.Seconds.ToString & "." & span.Milliseconds

            DataGridView1.Rows.Add(i, StopwatchLabel.Text, lapTime)
        Else
            DataGridView1.Rows.Add(i, StopwatchLabel.Text, StopwatchLabel.Text)
        End If
        Label3.Text = Label3.Text + Val(1)
    End Sub

 

[BleepyEvans]

Would really apprieciate if someone could help me with this. My whole application practically revolves around this one big thing

If someone wants to look at my source please just let me know.

 

[BleepyEvans]

Doesnt matter, I had to go a long way round, using more timers and hidden labels.

I think its slightly less acurate too, maybe a bit of a delay.