title: C# one event for multi textbox
body: <p>I have textbox4 = textbox1 + textbox2 + textbox3 . i want when textbox1 or textbox2 or textbox3 changed textbox4 auto show value.
  I have code:</p>
  
  <pre><code> private void textbox1_TextChanged(object sender, TextChangedEventArgs e)
      {
          try
          {
              textbox4.Text = ((float.Parse(textbox1.Text) + float.Parse(textbox2.text)+ float.Parse(textbox3.text)).ToString();
  
          }
          catch 
          {
  
          }
  
      }
   private void textbox1_TextChanged(object sender, TextChangedEventArgs e)
      {
          try
          {
             textbox4.Text = ((float.Parse(textbox1.Text) + float.Parse(textbox2.text)+ float.Parse(textbox3.text)).ToString();
  
          }
          catch 
          {
  
          }
  
      }
   private void textbox1_TextChanged(object sender, TextChangedEventArgs e)
      {
          try
          {
             textbox4.Text = ((float.Parse(textbox1.Text) + float.Parse(textbox2.text)+ float.Parse(textbox3.text)).ToString();
  
          }
          catch 
          {
  
          }
  
      }
  </code></pre>
  
  <p>Now I want to make it simpler. Shorten the code. Only declare the action 1 time.
  Like: textbox1 or textbox2 or textbox3 changes the tense textbox4 = textbox1 + textbox2 + textbox3</p>