null/empty value problem

Question

For any null/empty value this code does not work. Please help me. string TotalQty = (Convert.ToInt32(_product.Where(x => x.Type.ToLower() == row.Cells[0].Value.ToString().ToLower()).Select(x => x.TotalQty).FirstOrDefault()) + Convert.ToInt32(row.Cells[3].Value.ToString())).ToString();

Ramesh Palanivel · Answer

Hi Shovan Now what error you are getting in your code?

Puneet Kankar · Answer

try this if (string.IsNullOrEmpty(myString)) { // }

Shovan Saha · Answer

Dear Ramesh Sir when I get null/empty value for Price or Quantity then the error occurs. Please sir help me at this regard. An unhandled exception of type 'System.InvalidCastException' occurred in mscorlib.dll Additional information: Unable to cast object of type 'WhereSelectListIterator`2[WindowsFormsApplication1.ProductListSystem.String]' to type 'System.IConvertible'.

Shovan Saha · Answer

Dear Puneet Sir I am new in code. Please edit my code : private void Form1_Load(object sender EventArgs e) { AddRowsInDatagridView(0L A 3 2); AddRowsInDatagridView(1M B 4 3); AddRowsInDatagridView(2L A 5 7); AddRowsInDatagridView(3M B   8); AddRowsInDatagridView(4L A 3 5); AddRowsInDatagridView(5S S 2 9); AddRowsInDatagridView(6S S 1 12); dataGridView2.Visible = false; } public void AddRowsInDatagridView(int rowstring Type string Item string Price string Qty) { dataGridView1.Rows.Add(); dataGridView1.Rows[row].Cells[0].Value = Type; dataGridView1.Rows[row].Cells[1].Value = Item; dataGridView1.Rows[row].Cells[2].Value = Price; dataGridView1.Rows[row].Cells[3].Value = Qty; } private void button1_Click(object sender EventArgs e) { dataGridView2.Visible = true; List _product = new List (); int Count = 1; foreach (DataGridViewRow row in dataGridView1.Rows) { if (row.Cells[0].Value !=  && row.Cells[0].Value != null) { if (_product.Where(x => x.Type.ToLower() == row.Cells[0].Value.ToString().ToLower()).Any()) { string TotalQty = (Convert.ToInt32(_product.Where(x => x.Type.ToLower() == row.Cells[0].Value.ToString().ToLower()).Select(x => x.TotalQty).FirstOrDefault()) + Convert.ToInt32(row.Cells[3].Value.ToString())).ToString(); string TotalPrice = (Convert.ToInt32(_product.Where(x => x.Type.ToLower() == row.Cells[0].Value.ToString().ToLower()).Select(x => x.TotalPrice).FirstOrDefault()) + Convert.ToInt32(row.Cells[2].Value.ToString())).ToString(); _product.Where(x => x.Type.ToLower() == row.Cells[0].Value.ToString().ToLower()).ToList().ForEach(x => { x.TotalQty = TotalQty; x.TotalPrice = TotalPrice; }); } else { _product.Add(new ProductList { Sno = Count Type = row.Cells[0].Value.ToString() Item = row.Cells[1].Value.ToString() TotalPrice = row.Cells[2].Value.ToString() TotalQty = row.Cells[3].Value.ToString() }); Count++; } } } dataGridView2.DataSource = _product; }