图形界面程序的事件处理，实现简易计算器，程序运行之后，当输入两个运算数后，点击“相加”或者“相减”按钮，两数相加或相减的结果就会显示在“运算结果”框中。 如果点击“全部清零”按钮，那么两个运算数输入框和运算结果框中就会完全被清空。-Event processing graphical interface program to achieve a simple calculator, after the running of the program, when the input of the two operands, click " add"　or " subtract"　button, the two numbers added or subtracted results will be displayed in The result of the operation box. If you click on the " all clear"　button, then the two operands input box and the result of the operation box will completely emptied.