Validating a numeric textbox

Question

I'm trying to validate a textbox to check that it has a phone number type value entered.

The problem I'm having is that even when the entry is for example: "blah" in these text boxes the Regex is still returning false and no error message is shown.

Regex staffNumVal = new Regex(@"^[a-z]+$");

if (staffNumVal.IsMatch(txtStaffHPhone.Text)||(staffNumVal.IsMatch(txtStaffHourRate.Text)))
{
   MessageBox.Show("Please enter a numeric value");
}

Is there a better way to do this that I'm missing? Thanks.

Can you be sure there is no whitespace? If your values need trimming or contain whitespace that Regex won't match... — Paul D'Ambra, Nov 06 '12 at 12:10

score 2 · Answer 1 · answered Nov 06 '12 at 12:07

Instead of

Regex staffNumVal = new Regex(@"^[a-z]+$");

Use

Regex staffNumVal = new Regex(@"^[0-9]+$");

if (staffNumVal.IsMatch(txtStaffHPhone.Text)||(staffNumVal.IsMatch(txtStaffHourRate.Text)))
{
  //Valid
}
else
{
  MessageBox.Show("Please enter a numeric value");
}

score 1 · Answer 2 · answered Nov 06 '12 at 12:08

1

Regex staffNumVal = new Regex(@"^\d*$");

answered Nov 06 '12 at 12:08

Danilo Vulović

2,983
20
31

score 0 · Answer 3 · answered Nov 06 '12 at 12:07

0

Try it like so

int value;
if (int.TryParse(txtStaffHPhone.Text, out value))
{
    // it's a valid integer 
}

answered Nov 06 '12 at 12:07

Mihai

2,740
31
45

1

if value is grater then int MaxValue, this will fail – m4ngl3r Nov 06 '12 at 12:13

score 0 · Answer 4 · edited May 23 '17 at 11:48

0

Regex regex = new Regex(@"^\d$");

Refer for Details: Regex for numbers only

edited May 23 '17 at 11:48

Community

1
1

answered Nov 06 '12 at 12:12

andy

5,979
2
27
49

score 0 · Answer 5 · answered Nov 06 '12 at 12:28

Your RegEx does not do what you expect it.

I think the '^' is misplaced. It should be: @"[^a-z]+$".

But even that is wrong, since it accepts things like &.

You can test at: http://regexhero.net/tester/

But I think you'll be better served with a MaskedTestBox. Have you tried that?

Validating a numeric textbox

5 Answers5