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MessageBox Class

Displays a message box that can contain text, buttons, and symbols that inform and instruct the user.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
public class MessageBox

You cannot create a new instance of the MessageBox class. To display a message box, call the static method MessageBox.Show. The title, message, buttons, and icons displayed in the message box are determined by parameters that you pass to this method.

The following code example shows how to use a MessageBox to inform the user of a missing entry in a TextBox. This example requires that the method is called from an existing form with a Button and a TextBox on it.

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    const string message =
        "Are you sure that you would like to close the form?";
    const string caption = "Form Closing";
    var result = MessageBox.Show(message, caption,
                                 MessageBoxButtons.YesNo,
                                 MessageBoxIcon.Question);

    // If the no button was pressed ... 
    if (result == DialogResult.No)
    {
        // cancel the closure of the form.
        e.Cancel = true;
    }
}

The following code example shows how to ask the user a yes or no question and make a decision based on the response.

	private void validateUserEntry()
	{

		// Checks the value of the text. 

		if(serverName.Text.Length == 0)
		{

			// Initializes the variables to pass to the MessageBox.Show method.

			string message = "You did not enter a server name. Cancel this operation?";
                        string caption = "Error Detected in Input";
			MessageBoxButtons buttons = MessageBoxButtons.YesNo;
			DialogResult result;

			// Displays the MessageBox.

			result = MessageBox.Show(message, caption, buttons);

			if (result == System.Windows.Forms.DialogResult.Yes)
			{

				// Closes the parent form. 

				this.Close();

			}

		}

	}
System.Object
  System.Windows.Forms.MessageBox
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0
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