C Numeric Only TextBox Control

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

User · Answer

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  lt  Keys D0    e KeyCode  gt  Keys D9                   Determine whether the keystroke is a number from the keypad          if  e KeyCode  lt  Keys NumPad0    e KeyCode  gt  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

User · Answer

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

User · Answer

try       int temp Convert ToInt32 TextBox1 Text     catch Exception h        MessageBox Show  Please provide number only

User · Answer

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

User · Answer

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

User · Answer

I think it will help you   lt script type  text javascript  gt  function isNumberKey evt        var charCode    evt which    evt which   event keyCode     if  charCode  gt  32  amp  amp   charCode  lt  48    charCode  gt  57   amp  amp   charCode    45   amp  amp   charCode    43   amp  amp   charCode    40   amp  amp   charCode    41           return false       return true

User · Answer

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

User · Answer

use this code   private void textBox1 KeyPress object sender  KeyPressEventArgs e                        const char Delete    char 8              e Handled    Char IsDigit e KeyChar   amp  amp  e KeyChar    Delete

User · Answer

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

User · Answer

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   amp  amp  e KeyChar    Delete

[c#] C# Numeric Only TextBox Control

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