Items are being replaced by another in the Datagridview

When I add the first item in the DataGridView it's OK but when I add the second one it replaces the last item added.

Private Sub add()

    Dim i As Integer
    For i = 0 To DataGridView1.Rows.Count - 1
        'DataGridView1.Rows.Add()
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("TransID").Value = txttrans.Text
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("ProductCode").Value = txtprodcode.Text
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("ProductName").Value = cmbprodname.Text
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("Quantity").Value = txtqty.Text
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("Price").Value = txtprc.Text
        DataGridView1.Rows(DataGridView1.RowCount开发者_运维技巧 - 1).Cells("Amount").Value = txtat.Text
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("CustomerName").Value = txtcust.Text
        DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("Date1").Value = txtdate.Text
       
    Next i

  
End Sub

And this is in my ADDbutton:

Private Sub btnadd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnadd.Click
    
    Try
        add()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
    Dim total As Integer

    For Each row As DataGridViewRow In DataGridView1.Rows

        total += row.Cells("Amount").Value

    Next

    txtamt.Text = total

Should this (and the other lines)

DataGridView1.Rows(DataGridView1.RowCount - 1).Cells("TransID").Value = txttrans.Text

not be

DataGridView1.Rows(i).Cells("TransID").Value = txttrans.Text

because otherwise you are just addint the row DataGridView1.RowCount - 1.

Try the following. Create a datatable with with the data structue that you need. I provided a small example of what to do. The data column array contains the column information. dt.columns.addRange sets your columns to the desired column name structure. The dt.newRow() method returns an empty row but contains the necessary schema so that you won't get the error that you are getting. Once you have added all the rows necessary you can reference the rows in the datatable using row["columnName"]

Use datagridview.datasource = dt to bind the datagrid to the datatable object.

  public Form1()
    {
        DataColumn column0 = new DataColumn("TransID");
        DataColumn column1 = new DataColumn("Price");
        DataColumn column2 = new DataColumn("Quantity");

        columns[0] = column0;
        columns[1] = column1;
        columns[2] = column2;

        DataTable dt = new DataTable();
        dt.Columns.AddRange(columns);

        //Creates a datarow object based on the dataable's schema
        DataRow row = dt.NewRow();

        row["TransID"] = "Transaction Text";
        row["Price"] = "Price Text";
        row["Quantity"] = "Quantity";

        //Add the row to the dataTable
        dt.Rows.Add(row);

        dataGridView1.DataSource = dt;
    }