Allow user to only enter numbers in textbox and if character entered then clear the textbox along with a message

Question

Hey guys, How can i allow users to enter only numbers in a textbox? And if they enter a character then i erase that character and give a message?

I tried this:

private void txtInventoryManagerCostPrice_KeyPress(object sender, KeyPressEventArgs e)
          {
              char keypress = e.KeyChar;
              if (keypress == Convert.ToChar(Keys.D0) || keypress == Convert.ToChar(Keys.D1) || keypress == Convert.ToChar(Keys.D2) || keypress == Convert.ToChar(Keys.D3) || keypress == Convert.ToChar(Keys.D4) || keypress == Convert.ToChar(Keys.D5) || keypress == Convert.ToChar(Keys.D6) || keypress == Convert.ToChar(Keys.D7) || keypress == Convert.ToChar(Keys.D8) || keypress == Convert.ToChar(Keys.D9) || keypress == Convert.ToChar(Keys.NumPad0) || keypress == Convert.ToChar(Keys.NumPad1) || keypress == Convert.ToChar(Keys.NumPad2) || keypress == Convert.ToChar(Keys.NumPad3) || keypress == Convert.ToChar(Keys.NumPad4) || keypress == Convert.ToChar(Keys.NumPad5) || keypress == Convert.ToChar(Keys.NumPad6) || keypress == Convert.ToChar(Keys.NumPad7) || keypress == Convert.ToChar(Keys.NumPad8) || keypress == Convert.ToChar(Keys.NumPad9))
              {

              }
              else if (keypress == Convert.ToChar(Keys.Back))
              {

              }
              else
              {
                  MessageBox.Show("You Can Only Enter A Number!");
                  txtInventoryManagerCostPrice.Text = "";
              }
          }

But this code allows characters 'a' through 'i'. Which i don't want. Help would be appreciated.

Regards,

Rayyan Tahir

Answer 1

This is actually a common task - instead of re-writing something like this you will find that people have been nice and already created this control for you.

Microsoft's .Net 4 Masked TextBox: http://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.aspx

//Add to the textbox's KeyPress event
private void txtBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (!System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), "\\d+"))
e.Handled = true;
}

Add your message in the above event.

Another nice NumericTextBox control from the code project: http://www.codeproject.com/Articles/42382/Creating-a-Numeric-TextBox-Control

Have fun.

---

Digital Forensic Software Developer
CCS LABS Digital Forensic Software
Mark as Answer or Vote up if useful thank you!

Answer 2

Check this It will works fine.,..

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            int i = e.KeyChar;
            if (i >= 48 && i <= 57)
            {              
            }
            else
            {
                MessageBox.Show("You Can Only Enter A Number!");
                e.Handled = true;
            }
        }

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If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful"

Answer 3

Hi try this code

 char keypress = e.KeyChar;
            if (char.IsDigit(keypress) || e.KeyChar==Convert.ToChar(Keys.Back))
            {
            

            }
            else
            {
                MessageBox.Show("You Can Only Enter A Number!");
                e.Handled = true;
            }

---

By Sanz. -- If you find this post helpful then please "Vote as Helpful" and "Mark As Answer".

Answer 4

Thank You San Sanz. This is just what i was looking for. Thanks a bunch!

Best regards

Answer 5

Thank you that would help me as well. But i have too many text boxes already in my application that it would simply take me time to re-add them as masked textboxes. My bad for not adding in the details =). Thanks! =)

Answer 6

thanks