用于处理winfrom编程中，文本输入框只能输入数字，禁止用户输入字母的方法。在该文本框的KeyPress事件上调用该方法 就可以成功控制用户输入-For handling winfrom programming, text input box can only enter numbers, letters against the user input method. In the text box KeyPress event to call the method can successful