Validating a Textbox window form

Question

1.00/5 (1 vote)

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.NET3.5

Hi guys i am trying to validate a textbox to accecpt only numbers within a specified range, but it is not working, any idea what to do.. Thanks in advance

Posted 8-Jun-12 4:07am

IamBlessed

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Manas Bhardwaj 8-Jun-12 10:16am

What kind of code you are using?

IamBlessed 8-Jun-12 10:29am

I have tried using the NumericUpDown class, but it is not working since my values are decimal, i also tried using int32.parse(mytextbox) then use a if statement to check it agaisnt the range. But still did not work, the Range are 0.01 - 0.90

Sergey Alexandrovich Kryukov 8-Jun-12 10:31am

"Not working" is not descriptive. What's the problem? Do you have a code sample to manifest the problem?
--SA

IamBlessed 8-Jun-12 10:34am

int val = 0;
bool res = Int32.TryParse(Ca_TxtBx.Text, out val);
if (res == true && val > 0.01 && val < 0.90)
{
// Do something
}
else
{
MessageBox.Show("Please input 0.01 to 0.90 only.");
}

and this

NumericUpDown control = new NumericUpDown();

decimal max = Convert.ToDecimal(0.90);
decimal min = Convert.ToDecimal(0.01);

control.Minimum = min;
control.Maximum = max;

if (Convert.ToDecimal(Ca_TxtBx.Text) > control.Maximum || Convert.ToDecimal(Ca_TxtBx.Text) < control.Minimum)
{
MessageBox.Show("Please input 0.01 to 0.90 only.");

}

it does not validate the texbox..

Clifford Nelson 8-Jun-12 12:13pm

Are you doing winforms or WPF?

IamBlessed 8-Jun-12 15:30pm

Window form

Clifford Nelson 8-Jun-12 16:17pm

So what do you think of limiting only to number keys?

2 solutions

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Manas Bhardwaj · Accepted Answer · 2012-06-08T04:50:00

Solution 1

Use regular expression:

C#

string num = "0.7";

Regex pattern = new Regex(@"^[0]+(.[0-9]{1,2})?$");

if (pattern.Match(num).Success)
{
    Console.WriteLine("OK");
}

The above code will validate decimal numbers greater than 0 and less than 1, upto 3 decimal places.

Posted 8-Jun-12 4:50am

Manas Bhardwaj

Comments

Maciej Los 8-Jun-12 11:03am

Good answer, my 5!

Manas Bhardwaj 8-Jun-12 11:12am

Thanks!

IamBlessed 8-Jun-12 11:25am

Thanks for the answer

Clifford Nelson · Accepted Answer · 2012-06-08T06:19:00

Solution 2

Easier just to prevent any but numeric keys in the KeyPress event for the textbox. This is how you do it in WinForms:

C#

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

May want to do a beep or something when an non-digit key is pressed: See http://msdn.microsoft.com/en-us/library/h62wtc8c.aspx[^]

Posted 8-Jun-12 6:19am

Clifford Nelson

Updated 8-Jun-12 6:27am

v2

Comments

IamBlessed 8-Jun-12 16:21pm

Thanks For your answer this has been very useful