有理数是一个可以化为一个分数的数，例如2/3，533/920，-12/49都是有理数，而就为无理数。在C++中，并没有预先定义有理数。需要时可以定义一个有理数类，将有理数的分子和分母分别存放在两个整型变量中。对有理数的各种操作都可以用重载运算符来实现。-Is a rational number can be reduced to a fraction, such as 2/3, 533/920,-12/49 are rational numbers, and for an irrational number. In C++, there is no pre-defined rational number. Necessary to define a rational number class, will be the numerator and denominator of rational numbers are stored in two integer variables. Various operations on the rational use of overloaded operators can be achieved.