CausesValidation Property
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Control.CausesValidation Property


Gets or sets a value indicating whether the control causes validation to be performed on any controls that require validation when it receives focus.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public bool CausesValidation { get; set; }

Property Value

Type: System.Boolean

true if the control causes validation to be performed on any controls requiring validation when it receives focus; otherwise, false. The default is true.

If the CausesValidation property is set to false, the Validating and Validated events are suppressed.

The CausesValidation property value is typically set to false for controls such as a Help button.

The following code example uses the derived classTextBox and validates an e-mail address that the user enters. If the e-mail address is not in the standard format (containing "@" and "."), the validation fails, an ErrorProvider icon is displayed, and the event is canceled. One of the buttons on the form has its CausesValidation property set to false. Clicking or setting focus to this button does not trigger validation. This example requires that a TextBox, an ErrorProvider control, and a Button have been created on a form.

public Form1()
    //Set button2 to be non-validating.
    this.button2.CausesValidation = false;

private void textBox1_Validating(object sender, 
 				System.ComponentModel.CancelEventArgs e)
   string errorMsg;
   if(!ValidEmailAddress(textBox1.Text, out errorMsg))
      // Cancel the event and select the text to be corrected by the user.
      e.Cancel = true;
      textBox1.Select(0, textBox1.Text.Length);

      // Set the ErrorProvider error with the text to display. 
      this.errorProvider1.SetError(textBox1, errorMsg);

private void textBox1_Validated(object sender, System.EventArgs e)
   // If all conditions have been met, clear the ErrorProvider of errors.
   errorProvider1.SetError(textBox1, "");
public bool ValidEmailAddress(string emailAddress, out string errorMessage)
   // Confirm that the e-mail address string is not empty.
   if(emailAddress.Length == 0)
      errorMessage = "e-mail address is required.";
         return false;

   // Confirm that there is an "@" and a "." in the e-mail address, and in the correct order.
   if(emailAddress.IndexOf("@") > -1)
      if(emailAddress.IndexOf(".", emailAddress.IndexOf("@") ) > emailAddress.IndexOf("@") )
         errorMessage = "";
         return true;

   errorMessage = "e-mail address must be valid e-mail address format.\n" +
      "For example '' ";
      return false;

.NET Framework
Available since 1.1
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