定义分数类，可以对分数类对象的各种操作进行重载运算。表达式中可含有加、减、乘、除运算符以及实型数据的运算对象，并计算出结果显示出来。程序可以直接输入数学表达式，不需要任何转换，就可以直接输出数学四则运算和逻辑运算的结果。-Definition of class scores, scores of class objects can be overloaded various operations. Expression may contain addition, subtraction, multiplication and division operators and operands Real data and calculated results are displayed. Program can directly enter mathematical expressions, without any conversion, you can directly output mathematical arithmetic and logical result of the operation.