TextBox - Valid

[GNilsson]

I'm doing a calculation program and I only want numbers to be typed in the TextBox.

How do I make a validation so letters and other characters can't be typed.

I thought this was simple but I can´t find the key.


Thank you for the attention!

[CPCericola]

You will want to consume the TextBox.KeyPress event. You then check the value of the KeyPressEventArgs.KeyChar. If it's not within your range, you set e.handled = true.

Here's a code snipped to better explain it:

   void keypressed(Object o, KeyPressEventArgs e)
   {
      if(e.KeyChar < 'a' || e.KeyChar > 'z')
      {
        e.Handled = true;  // prevent from passing back to Windows for handling.
      }
         
   }

HTH.

[Gjain]

The above method can only be used for System.Windows.Forms TextBox not for a webform textbox.

[Gjain]

Add this code to InitializeComponent() function:

this.TextBox.KeyPress += new
System.Windows.Forms.KeyPressEventHandler(this.TextBox_KeyPress);


and this to the code:
private void TextBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
if ((e.KeyChar!=(char)8)&&(e.KeyChar!=(char)32)&&(!Char.IsDigit(e.KeyChar)) )
//the ASCII character code for SAPCE is 32 and BACKSAPCE is 8
{
e.Handled=true;
}
}

the above fn will allow only digits, space and backspace to be typed in the textbox.
Hope this helps.

[GNilsson]

Thank you for your help!!

It´s working fine. The program is a windows application but the goal is to make it a web application. As I´m a beginner at C#, I have to start somewhere.