The simplest form of modal dialog box is the message box. Most applications use message boxes to warn the user of errors and to prompt for directions on how to proceed after an error has occurred. You create a message box by using the MessageBox or MessageBoxEx function, specifying the message and the number and type of buttons to display. The system creates a modal dialog box, providing its own dialog box template and procedure. After the user closes the message box, MessageBox or MessageBoxEx returns a value identifying the button chosen by the user to close the message box.
In the following example, the application displays a message box if the fError variable is TRUE. The message box displays the message describing the error. The MB_OKCANCEL style directs MessageBox to provide two buttons with which the user can choose how to proceed:
if (fError)
{
if (MessageBox(hwndDlg, SZNOTFOUND, SZDELETEITEM,
MB_OKCANCEL)==IDOK)
{
// Prompt for a new item name and repeat the command.
}
else
{
// Cancel the command.
}
}
In this example, SZNOTFOUND and SZDELETEITEM are application-defined, null-terminated strings that represent the message text and the title for the message box.