计算列DataGridView-C＃

Question

I am trying to get a calculated column in DataGridView, at first I thought it was simple but now I have been struggling for an hour. The code below works fine when editing columns:

private void ReceiptDataGrid_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{            
    DataGridViewRow RecieptRow = RecieptDataGrid.Rows[e.RowIndex];
    RecieptRow.Cells[4].Value = double.Parse(RecieptRow.Cells[2].Value.ToString()) * double.Parse(RecieptRow.Cells[3].Value.ToString());            
}

But I am struggling to make the column take its value automatically when new rows are added. I get a NullReferenceException exception when I use the same code. I have tried a for loop and got the same error

private void RecieptDataGrid_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
{
   for (int i = 0; i < e.RowCount; i++)
  {
       DataGridViewRow RecieptRow = RecieptDataGrid.Rows[e.RowIndex + i];
      RecieptRow.Cells[4].Value = double.Parse(RecieptRow.Cells[2].Value.ToString()) * double.Parse(RecieptRow.Cells[3].Value.ToString());         
  }                       
}

I Realize that it sees the cells at nulls about is there a workaround to this? Help please.

Thank You.

Answer 1

you could check if your RecieotRow is a new row (with empty values) by using the IsNewRow property:

for (int i = 0; i < e.RowCount; i++)
{
   DataGridViewRow RecieptRow = RecieptDataGrid.Rows[e.RowIndex + i];

   if (RecieptRow.IsNewRow) continue;

   RecieptRow.Cells[4].Value = double.Parse(RecieptRow.Cells[2].Value.ToString()) * double.Parse(RecieptRow.Cells[3].Value.ToString());         
}  

Answer 2

I found the problem, it was reading the row default values as nulls. I replaced the default properties by adding the default value to the string that adds data to the DataGrid.