Only number, dot, and backspace.

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I think this question is really easy, but nonetheless, i coulnd't find it.

My current textbox has the ability to accept numbers, and backspace.
But the input has to be a float variabel, whitch means that i'll need dots (comma's?) as well.

private void tb_Stash_KeyPress(object sender, KeyPressEventArgs e)
{
  if (!char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar))
    e.Handled = true; 
}

What can I do to acomplish this?

Posted 30-Mar-11 1:15am

Amateurgrammer

Updated 30-Mar-11 1:20am

JF2015

v2

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4 solutions

Solution 3

Make an extension method that does the appropriate comparison:

C#

public static class ExtensionMethods
{
    public static bool IsCharacter(this char c, char thatChar)
    {
        return (c == thatChar);
    }
}

And call it this way:

C#

e.Handled = (!char.IsDigit(e.KeyChar)   && 
             !char.IsControl(e.KeyChar) && 
             !char.IsCharacter(System.Threading.Thread.CurrentThread.CurrentCulture.NumberFormat.CurrencyDecimalSeparator.GetAt(0)));

If you want to, you can also account for the CurrencyGroupSeparator.

Posted 30-Mar-11 1:31am

#realJSOP

Updated 30-Mar-11 8:54am

v2

Comments

RaviRanjanKr 30-Mar-11 14:59pm

Nice Answer. my 5 :)

Solution 4

Something like this would do it for you for any kind of culture ('.' or ','):

C#

private void tb_Stash_KeyPress(object sender, KeyPressEventArgs e)
{
  System.Globalization.CultureInfo c = System.Globalization.CultureInfo.CurrentUICulture;
  char dot = (char)c.NumberFormat.NumberDecimalSeparator[0];
  if (!char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar) && !e.KeyChar.Equals(dot))
    e.Handled = true;
}

Posted 30-Mar-11 1:33am

Amund Gjersøe

Updated 30-Mar-11 1:35am

v2

Comments

Manfred Rudolf Bihy 30-Mar-11 7:36am

That's good! 5+

Solution 2

if (!char.IsNumber(e.KeyChar) & (Keys)e.KeyChar != Keys.Back 
& e.KeyChar != '.')

I think comma will not be needed

Posted 30-Mar-11 1:30am

Om Prakash Pant

Comments

Manfred Rudolf Bihy 30-Mar-11 7:35am

It is where I come from since the decimal separator in Germany is the comma and not the period.

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Manfred Rudolf Bihy · Accepted Answer · 2011-03-30T01:28:00

You could use a different approach that will be more lenient to changing requirements due to locale. Try to parse what has been input into the TextBox with Double.TryParse(...) and accept the input only when parsing was successfull:

C#

private void tb_Stash_KeyPress(object sender, KeyPressEventArgs e)
{
    String alreadyInput = tb_Stash.Text;
    String wouldBe      = alreadyInput + e.KeyChar;
    Double shouldBe;
    if(!Double.TryParse(wouldBe, out shouldBe))
    {
        e.Handled = true;
    }
    else
    {
        //You could do something with shouldBe here if you wanted
    }
}

Best Regards,

Only number, dot, and backspace.

4 solutions

Solution 3

Solution 4

Solution 1

Solution 2

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