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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
public class MessageBox
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 button1_Click(object sender, System.EventArgs e) {
   if(textBox1.Text == "") {
      MessageBox.Show("You must enter a name.", "Name Entry Error",
         MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
   }
   else {
      // Code to act on the data entered would go here.
   }
}

protected void button1_Click(Object sender, System.EventArgs e)
{
    if (textBox1.get_Text().Equals("")) {
        MessageBox.Show("You must enter a name.", "Name Entry Error",
            MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
    }
    else {
        // Code to act on the data entered would go here.
    } 
} //button1_Click

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 == DialogResult.Yes)
        {

            // Closes the parent form.

            this.Close();

        }

    }

}


private void ValidateUserEntry()
{
    // Checks the value of the text.
    if (serverName.get_Text().get_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 = "No Server Name Specified";
        MessageBoxButtons buttons = MessageBoxButtons.YesNo;
        DialogResult result;

        // Displays the MessageBox.
        result = MessageBox.Show(this, message, caption, buttons);

        if (result.Equals(DialogResult.Yes)) {
            // Closes the parent form.
            this.Close();
        }
    }
} //ValidateUserEntry

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

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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