Forcing Text box to have only integer values

Question

4.57/5 (7 votes)

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I need a Text box that can only have integer values.
when user click the ok button, it should check whether the input in text box is an integer value, and if it isn't an integer value then it should show the message to enter only integer value.
and should reset the value to null.

I have done it this way.

C#

private void ok_Click(Object sender, EventAegs e)
{
   if(System.Text.regularExpressions.Regex.IsMatch("[^0-9]",exp_weight.Text))
    {
        ok=true;
        this.Hide();    
    }
    else{
    MessageBox.Show("Please Enter Number Only");
    exp_weight.Text=="";  
    } 
}

But this only work for the number 0 or 9, for any number other then this it shows the message "Please enter Number Only".

Now can some body help me??

Thanks

Posted 12-Feb-11 0:35am

hanifuk

Updated 12-Feb-11 1:49am

TweakBird

v3

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6 solutions

Solution 3

This[^] solution may be another way of achieving this task.

Posted 12-Feb-11 0:56am

Abhinav S

Comments

Sergey Alexandrovich Kryukov 12-Feb-11 22:21pm

I voted 4 this time. The reference can give right idea, but the implementation should definitive (no options, there is only one which is adequate), also, the simple solution is not there.
--Sa

Abhinav S 13-Feb-11 0:21am

I see what you mean.

Sergey Alexandrovich Kryukov 13-Feb-11 13:42pm

Thanks for understanding.
--SA

Solution 2

Hi Hanifuk,

If you need to check if the user input is integer or not you can try this :

int i;
bool parsed = int.TryParse(Convert.ToString(textBox1.Text), out i);

if the value is integer the i variable will be set to the converted integer and the parsed boolean variable will be 'true'
else the i variable will be set to 0 and the parsed boolean variable will be 'false'

I hope this helps you,
:)

Posted 12-Feb-11 0:53am

Michael Waguih

Updated 12-Feb-11 21:08pm

v2

Comments

Olivier Levrey 12-Feb-11 7:37am

isn't 0 an int value? Unless 0 must be considered as an invalid value, it remains an int and therefore your solution is not enough... I would rather use the Parse method since it throws an exception if the value can't be converted into an int.

GenJerDan 12-Feb-11 7:45am

Um...no. "i" be the integer value of the text if it was an "integer string". The return value is 0 or 1, depending on whether it successfully parsed.

Olivier Levrey 12-Feb-11 7:50am

Check MSDN about the int parameter: "When this method returns, contains the 32-bit signed integer value equivalent to the number contained in s, if the conversion succeeded, or zero if the conversion failed.". What you are talking about the return value of the TryParse method: true or false whether the functions succeeds or not.

GenJerDan 12-Feb-11 18:13pm

Yep. No 1 or 0. The number or 0, and a bool telling you its status.

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Henry Minute · Accepted Answer · 2011-02-12T02:15:00

Solution 4

The solution you use will depend on how you want the checking to be done.

If you want to prevent the user from being able to enter a non-numeric character then all of the previous solutions will work.

If you want the user to be able to enter what they want and check the input at the end then you should investigate the TextBox.Validating event.

Posted 12-Feb-11 2:15am

Henry Minute

Comments

Sergey Alexandrovich Kryukov 12-Feb-11 22:21pm

Good point, my 5.
--SA

Toli Cuturicu · Accepted Answer · 2011-02-12T10:52:00

Solution 5

Don't use a TextBox! Use a NumericUpDown instead! Voila, problem automatically solved.

Posted 12-Feb-11 10:52am

Toli Cuturicu

Comments

Manfred Rudolf Bihy 12-Feb-11 16:57pm

My vote of 4:

You are right of course that it would a better way to go, but OP was specific about the TextBox part.
Upvoted to a five because some idiot thought he could vote a 2 without leaving reason. :)

Sergey Alexandrovich Kryukov 12-Feb-11 22:17pm

I up-vote by my 5. Note just to oppose to the idiot (apparently idiot, is anyone disagree?).
Even though OP requested TextBox, how do we know that OP know what she or he really wants? In real life this is often not the case; so your answer gives better idea.
--Sa

Sandeep Mewara · Accepted Answer · 2011-02-12T00:41:00

Solution 1

Google or search CodeProject for 'Masked Textbox'

You need to use onKeyPress event and then probably use regular experession or ASCII values to verify the key pressed and act accordingly.

Posted 12-Feb-11 0:41am

Sandeep Mewara

Comments

Olivier Levrey 12-Feb-11 7:35am

My 5. MaskedTextBox is what OP needs although I don't think he has to use OnKeyPress: the Mask property is enough and does the job.

Sandeep Mewara 12-Feb-11 7:47am

Details were to just explain how Masked textbox would work, such that in case OP wants can build own :)

MCY 12-Feb-11 12:13pm

Easiest and most elegant way imho

Sergey Alexandrovich Kryukov 12-Feb-11 22:19pm

No, masked text box can be very inconvenient, it is designed for more complex input.
Here, the task is simple, needs just filtering.
--SA

hanifuk 13-Feb-11 4:49am

Exactly :)

Shahin Khorshidnia · Accepted Answer · 2011-02-12T12:25:00

Hi,
I think it can help:

C#

private void ok_Click(object sender, EventArgs e)
{
    int k;
    if(int.TryParse(exp_weight.Text, out k))
    {
        ok=true;
        this.Hide();
    }
    else
    {
        MessageBox.Show("Please Enter Number Only");
        exp_weight.Text=string.Empty;
    }
}