C# wait for user to finish typing in a Text Box

Question

Is there a way in C# to wait till the user finished typing in a textbox before taking in values they have typed without hitting enter?

Revised this question a little:

Okay I have a simple calculator that multiplies by 2.

Here is what I want it to do: The user inputs a value like 1000 into a textbox and it automatically displays 2000.

Here is what happens: As soon as the user enters in 1 its multiplies by 2 and outputs 2.

Answer 1

I define "finished typing" now as "user has typed something but has not typed anything after a certain time". Having that as a definition i wrote a little class that derives from TextBox to extend it by a DelayedTextChanged event. I do not ensure that is complete and bug free but it satisfied a small smoke test. Feel free to change and/or use it. I called it MyTextBox cause i could not come up with a better name right now. You may use the DelayedTextChangedTimeout property to change the wait timeout. Default is 10000ms (= 10 seconds).

public class MyTextBox : TextBox {     private Timer m_delayedTextChangedTimer;      public event EventHandler DelayedTextChanged;      public MyTextBox() : base()      {         this.DelayedTextChangedTimeout = 10 * 1000; // 10 seconds     }      protected override void Dispose(bool disposing)     {         if (m_delayedTextChangedTimer != null)         {             m_delayedTextChangedTimer.Stop();             if (disposing)                 m_delayedTextChangedTimer.Dispose();         }          base.Dispose(disposing);                 }      public int DelayedTextChangedTimeout { get; set; }      protected virtual void OnDelayedTextChanged(EventArgs e)     {         if (this.DelayedTextChanged != null)             this.DelayedTextChanged(this, e);     }      protected override void OnTextChanged(EventArgs e)     {         this.InitializeDelayedTextChangedEvent();         base.OnTextChanged(e);                 }                      private void InitializeDelayedTextChangedEvent()     {         if (m_delayedTextChangedTimer != null)             m_delayedTextChangedTimer.Stop();          if (m_delayedTextChangedTimer == null || m_delayedTextChangedTimer.Interval != this.DelayedTextChangedTimeout)         {                             m_delayedTextChangedTimer = new Timer();             m_delayedTextChangedTimer.Tick += new EventHandler(HandleDelayedTextChangedTimerTick);             m_delayedTextChangedTimer.Interval = this.DelayedTextChangedTimeout;         }          m_delayedTextChangedTimer.Start();     }      private void HandleDelayedTextChangedTimerTick(object sender, EventArgs e)     {         Timer timer = sender as Timer;         timer.Stop();          this.OnDelayedTextChanged(EventArgs.Empty);     } } 

Answer 2

Another simple solution would be to add a timer to your form, set the Interval property to 250 and then use the timer's tick event as follows:

private void timer1_Tick(object sender, EventArgs e) {     timer1.Stop();     Calculate(); // method to calculate value }  private void txtNumber_TextChanged(object sender, EventArgs e) {     timer1.Stop();     timer1.Start(); }