C# Numeric Only TextBox Control [duplicate]

Question

I am using C#.NET 3.5, and I have a problem in my project. In C# Windows Application, I want to make a textbox to accept only numbers. If user try to enter characters message should be appear like "please enter numbers only", and in another textbox it has to accept valid email id message should appear when it is invalid. It has to show invalid user id.

Kliman

Answer 1

I suggest, you use the MaskedTextBox: http://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.aspx

Jackelynjackeroo

Answer 2

use this code:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            const char Delete = (char)8;
            e.Handled = !Char.IsDigit(e.KeyChar) && e.KeyChar != Delete;
        }

Godship

This does not prevent the user from pasting any text into the text box. – Prone

Answer 3

From C#3.5 I assume you're using WPF.

Just make a two-way data binding from an integer property to your text-box. WPF will show the validation error for you automatically.

For the email case, make a two-way data binding from a string property that does Regexp validation in the setter and throw an Exception upon validation error.

Look up Binding on MSDN.

Harlot

Answer 4

You might want to try int.TryParse(string, out int) in the KeyPress(object, KeyPressEventArgs) event to check for numeric values. For the other problem you could use regular expressions instead.

Pheidippides

Answer 5

I used the TryParse that @fjdumont mentioned but in the validating event instead.

private void Number_Validating(object sender, CancelEventArgs e) {
    int val;
    TextBox tb = sender as TextBox;
    if (!int.TryParse(tb.Text, out val)) {
        MessageBox.Show(tb.Tag +  " must be numeric.");
        tb.Undo();
        e.Cancel = true;
    }
}

I attached this to two different text boxes with in my form initializing code.

    public Form1() {
        InitializeComponent();
        textBox1.Validating+=new CancelEventHandler(Number_Validating);
        textBox2.Validating+=new CancelEventHandler(Number_Validating);
    }

I also added the tb.Undo() to back out invalid changes.

Counterscarp

Answer 6

this way is right with me:

private void textboxNumberic_KeyPress(object sender, KeyPressEventArgs e)
{
     const char Delete = (char)8;
     e.Handled = !Char.IsDigit(e.KeyChar) && e.KeyChar != Delete;
}

Giese

Answer 7

You can check the Ascii value by e.keychar on KeyPress event of TextBox.

By checking the AscII value you can check for number or character.

Similarly you can write logic to check the Email ID.

Currier

If I were the evil tester, I would paste some text... – Epirogeny

Answer 8

TRY THIS CODE

// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;
// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;
    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if (e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
}

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (nonNumberEntered == true)
    {
       MessageBox.Show("Please enter number only..."); 
       e.Handled = true;
    }
}

Source is http://msdn.microsoft.com/en-us/library/system.windows.forms.control.keypress(v=VS.90).aspx

Capitalization

What about cursor keys and delete key? If the OP uses Windows Forms, he could use Daniel's solution. – Epirogeny

One bug related to this one: Try pressing "SHIFT + 1" and see what happens. – Raleighraley

Answer 9

I think it will help you

<script type="text/javascript">
function isNumberKey(evt) {
    var charCode = (evt.which) ? evt.which : event.keyCode
    if (charCode > 32 && (charCode < 48 || charCode > 57) && (charCode != 45) && (charCode != 43) && (charCode != 40) && (charCode != 41))
        return false;

    return true;
}

Conscript

Answer 10

try
{
    int temp=Convert.ToInt32(TextBox1.Text);
}
catch(Exception h)
{
    MessageBox.Show("Please provide number only");
}

Maggio

what code are you trying to give the op? makes no sense – Lorin