C++中预定义的运算符的操作对象只能是基本数据类型，对于很多用户自定义类型，也需要有类似的运算操作，这就提出了对运算符进行重新定义，赋予已有符号以新功能的要求。-In C++ predefined operator operating the object can only be basic data types, for many user-defined types, operators also need to have a similar operation, which proposed a redefinition of the operator, has been given a new function symbol requirements.