CODEWITHSUNDEEP
c#winformstextbox
petya1969
petya1969

Reputation: 49

Enter only numbers 1 or 2

How can you make it so that only the numbers 1 or 2 can be entered into the textbox? And you can also use the Backspace key. The maximum length of textbox characters is one. I know how to enter only numbers:

char number = e.KeyChar;
if (!Char.IsDigit(number) && number != 8)
{
e.Handled = true;
}

Upvotes: 0

Views: 249

Answers (5)

Selçuk Güral
Selçuk Güral

Reputation: 92

Use SuppressKeyPress property

    private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        /*
         * 8:   backspace
         * 49:  1
         * 50:  2
         */

        int[] validKeys = {8, 49, 50};
        if (!validKeys.Contains(e.KeyValue))
            e.SuppressKeyPress = true;

    }

Upvotes: 1

TimB
TimB

Reputation: 1000

I'd use the NumericUpDown control instead of a TextBox. There you can set min to 1, max to 2, and your user can enter numbers or use the arrow keys to increase/decrease.

If you MUST use a TextBox, then set it MaxLength property to 1, and add a KeyDown event and handler. In the handler you can do:

if(!(e.KeyCode == Keys.D1 || e.KeyCode == Keys.D2 || E.KeyCode == Keys.Delete)) 
{
    // Of course, you can add even more keys up there. For example, you might add Keys.Numpad1 etc...
    e.handled = true;
}

So, for the TextBox you already did the right thing, basically.

Upvotes: 1

CSDev
CSDev

Reputation: 3235

char number = e.KeyChar;
if (number != '1' && number != '2' && number != '\b')
{
    e.Handled = true;
}

or just

e.Handled = e.KeyChar != '1' && e.KeyChar != '2' && e.KeyChar != '\b';

or for more expressiveness

private static readonly char[] allowedChars = { '1', '2', '\b' };
// ...
e.Handled = !allowedChars.Contains(e.KeyChar);

Upvotes: 1

fahime
fahime

Reputation: 179

All you need is use RegularExpressions and you can check any input with expressions.

I think you should visit this question: Only allow specific characters in textbox

Upvotes: 1

Toby Smith
Toby Smith

Reputation: 1605

I assume all you need is something like the following in the textbox's TextChanged event?

if (textbox.text != "1" && textbox.text != "2")
{
    textbox.text = string.empty;
}

I'm not sure what the number != 8 is for in your question?

Upvotes: 0

Related Questions