As in the last example, many applications have one place where the values (such as filenames, numeric values, and selected options) are displayed for output and another place where user input to them is accepted.

• 正如在最后一个例子中，很多程序都有一个显示输出值的地方（诸如文件名、数值及选择的项），而在另外一个地方接收用户的输入。