C# code to show datagridview cell value on Balloon Tooltip

You could probably use the CellMouseEnter event of the datagridview  and then use the eventargs of the event to get your value using e.ColumnIndex and e.RowIndex.
Once you get the value you could display that in a tooltip set as balloon style..

Please provide C# sample code

Here is VB code to get the info you need...I have never tried this so there might need to be some tweaks... I will try to convert as well..
 

    Private Sub DataGridView1_CellMouseEnter( _
                        ByVal sender As Object, _
                        ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) _
                        Handles DataGridView1.CellMouseEnter
 
        If e.RowIndex >= 0 And e.ColumnIndex >= 0 Then
 
            DataGridView1.CurrentCell = DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex)
            Dim s As String = DataGridView1.CurrentCell.Value
            MsgBox(s)
 
        End If
 
 
 
    End Sub

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Paste the code below into the event I mentioned...

    if (e.RowIndex >= 0 & e.ColumnIndex >= 0) { 
        
        DataGridView1.CurrentCell = DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex); 
        string s = DataGridView1.CurrentCell.Value; 
            
        Interaction.MsgBox(s); 
    } 

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Like I said...I didn't really do an error checking or validate much...good luck

    if (e.RowIndex >= 0 & e.ColumnIndex >= 0) { 
        
        DataGridView1.CurrentCell = DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex); 
            
        DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).ToolTipText = DataGridView1.CurrentCell.Value; 
    } 

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Last time...this would be better..

    if (e.RowIndex >= 0 & e.ColumnIndex >= 0) { 
        
        DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).ToolTipText = DataGridView1.CurrentCell.Value; 
    } 

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never mind that...I posted before I read the code...Go with the the second to last one.
 

Oh...and althought I am not certain, I think if you want a balloon tooltip then you need to add the tooltip control.  I am not sure you can change the type of tooltip built in to the grid...

The value show in Message Box [MessageBox.Show(s)], But not working in Balloon Tooltip, the default Tooltip show the value.

Shows in normal Tooltip, but not in Balloon Tooltip.

    if (e.RowIndex >= 0 & e.ColumnIndex >= 0) { 
        
        DataGridView1.CurrentCell = DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex); 
        this.mainToolTip.SetToolTip(DataGridView1, DataGridView1.CurrentCell.Value); 
            
        this.mainToolTip.Active = true; 
    } 

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I dropped a tooltip control on the form and then change the IsBalloon property to design view as well as some of the display delays.
Using the code above it worked as expected...

Please send your sample project as an attachment

I didn't create a sample project...

I am trying as per your instructions, but it is not working, please send a sample project containing the solution that you provided.

are you getting errors or what...
 

The call value Shows in normal Tooltip as well as Message Box, But NOT in Balloon Tooltip

First off, like I stated above, the default tooltip with the DataGridView should be set to FALSE.  If I don't do that on mine...it doesn't work.

I followed the same steps as above in an app I have, which already had a datasource for the grid, which I cannot upload.

sample.png

How you set the default tooltip value of DataGridView is FALSE.

Thankx..

Click on the DataGridView Control  in Design View.  Then in the Properties Window find the property called ShowCellToolTips.  Change it to False....
sample.png

Is it working now?

Yes

It is working

Instead of selecting almost every post I made as an answer, I think it would be more beneficial to those that come across this question if we split the points between ID: 24361883 (Tells how to setup the project) and ID: 24361947 (The final valid code posted.)
rgn