Check if int from textbox is empty + cast

Question

I have the following form:

My field Quantity should be an int but I want to implement error checking.

This is my code:

   private void btn_Create_Click(object sender, EventArgs e)
        {

            bool exit = false;

            if (String.IsNullOrEmpty(tb_Quantity.Text))
            {
                lbl_Error.Visible = true;
                lbl_Error.Text = "Check required values !";
                exit = true;
            }

            int Quantity = int.Parse(tb_Quantity.Text.Trim());


            if (!exit)
            {
                MessageBox.Show("Ready to be created!");
            }

        }

The error that I get if my quantity is empty:

An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll

Additional information: Input string was not in a correct format.

What am I doing wrong?

What framework are you using? – mahlatse Nov 23 '18 at 10:15 — mahlatse, Nov 23 '18 at 10:15
use `TryParse` instead of `Parse`. – MakePeaceGreatAgain Nov 23 '18 at 10:16 — MakePeaceGreatAgain, Nov 23 '18 at 10:16
WinForms is what i'm using – user3127554 Nov 23 '18 at 10:16 — user3127554, Nov 23 '18 at 10:16
are you sure you are passing `number` like this `"12"` – Saif Nov 23 '18 at 10:18 — Saif, Nov 23 '18 at 10:18

score 2 · Answer 1 · answered Nov 23 '18 at 10:16

2

Instead use TryParse() like below which won't throw exception in-case the casting fails (if it's NaN)

int.TryParse(tb_Quantity.Text.Trim(), out int quantity);

answered Nov 23 '18 at 10:16

Rahul

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Check if int from textbox is empty + cast

1 Answers1