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 successfully control the user input. .