实现一个计算器，界面类似WINDOWS中的界面，包括0~9十个数字、加、减、乘、除四种运算符号和一个用于输入及显示结果的文本框，单击每个按钮都能完成相应的功能。-Implement a calculator, WINDOWS interface similar to the interface, including the ten digits 0 to 9, add, subtract, multiply and divide four arithmetic symbols and text box for input and display of results, click each button can be completion of the corresponding functions.