NullReferenceException when trying to copy DataGridView

[chairmanPC]

I am trying to get my program in C# to copy and paste a selected row from one DataGridView to another DataGridView. Column 0 is the checkbox cell. The selected rows will be copied into the second DGV. But when I was trying to make this happen, I get NullReferenceException in this line: if ((bool)item.Cells[0].Value == true)

Here is what I did:

        private void btnAdd_Click(object sender, EventArgs e)
    {
        selectedDGV.Rows.Clear();
        foreach (DataGridViewRow item in allData.Rows)
        {
            if ((bool)item.Cells[0].Value == true)
            {
                int n = selectedDGV.Rows.Add();
                selectedDGV.Rows[n].Cells[0].Value = item.Cells[3].Value.ToString();
                selectedDGV.Rows[n].Cells[1].Value = item.Cells[4].Value.ToString();
                selectedDGV.Rows[n].Cells[2].Value = item.Cells[5].Value.ToString();
                selectedDGV.Rows[n].Cells[3].Value = item.Cells[6].Value.ToString();
                selectedDGV.Rows[n].Cells[4].Value = item.Cells[7].Value.ToString();
                selectedDGV.Rows[n].Cells[5].Value = item.Cells[8].Value.ToString();
            }
        }
    }

Here is my code to browse for file: `

private void button2_Click(object sender, EventArgs e) { try { //updateDataBtn.Enabled = true; selectedDGV.Rows.Clear(); importExcelToDataGridViewApp = new Microsoft.Office.Interop.Excel.Application();
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Title = "Browse for Excel File";
            ofd.Filter = "Excel and CSV Files|*.xlsx;*.csv";
            
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                textBox1.Text = ofd.FileName;
                importExcelToDataGridViewWorkbook = importExcelToDataGridViewApp.Workbooks.Open(ofd.FileName);
                importExcelToDataGridViewWorksheet = importExcelToDataGridViewWorkbook.ActiveSheet;
                importExcelToDataGridViewRange = importExcelToDataGridViewWorksheet.UsedRange;


                for (int rowIndex = 2; rowIndex <= importExcelToDataGridViewRange.Rows.Count; rowIndex++)
                {
                    allData.Rows.Add(null,importExcelToDataGridViewWorksheet.Cells[rowIndex, 1].Value,
                                            importExcelToDataGridViewWorksheet.Cells[rowIndex, 2].Value,
                                            importExcelToDataGridViewWorksheet.Cells[rowIndex, 3].Value,
                                             importExcelToDataGridViewWorksheet.Cells[rowIndex, 6].Value,
                                            importExcelToDataGridViewWorksheet.Cells[rowIndex, 7].Value,
                                             importExcelToDataGridViewWorksheet.Cells[rowIndex, 8].Value,
                                             importExcelToDataGridViewWorksheet.Cells[rowIndex, 9].Value,
                                             importExcelToDataGridViewWorksheet.Cells[rowIndex, 10].Value,
                                            null);
                }
            }
        }catch(Exception eee)
        {
            ErrorForm error= new ErrorForm();
            error.ShowDialog();
            error.label3.Text = eee.Message;
        }
    }

The data in the DGV's come from an excel file. How can I fix this problem?

 

[NoUserHere]

Mod move to Winfroms and fix code tag please.

 

[Skydiver]

Moved to WinForms and fixed code tags.

@chairmanPC : please post your questions to the appropriate subforum. Lately most of your questions have been about WinForms, not general VS.NET or C# programming, yet you continue to do so. I'd you are not sure what forum to post in, leave a note at the bottom to ask for it to be moved to a more appropriate forum.

 

[NoUserHere]

Debug your code, and put a break point on this line line 6 and after on int n = selectedDGV.Rows.Add();. You may find you have two problems.

Press f11 to step through your code and check at any point is n null?

I don't think you want to iterate over all of the rows. Shouldn't you be iterating over only those that are selected?

Shouldn't you be adding values in the add method?

 

[NoUserHere]

Look what happens when you add rows like you are, and look what also happens when you don't have a value set on a given cell.

What do you think the problem is?