说明：   集合的并、交、差集运算的实现 运用面向对象程序设计知识，利用C++语言设计和实现集合的并、交、差集运算，要求具备如下主要功能： （1）输入输出集合信息，集合元素类型可以是整数、实数或字符串 （2）判断集合的大小 （3）判断集合是否为空 （4）将集合置空 （5）在集合中查找指定的元素 （6）实现集合的交、并、差等运算 在实现过程中，需利用面向对象程序设计理论的基础知识，充分体现出C++语言关于类、继承、封装与多态等核心概念，每一个类应包含数据成员和成员函数。
(Collection of union, intersection, difference achieved using an object-oriented programming knowledge computing, the use of C++ language design and implementation of the collection, intersection, difference operation requires the following main functions: (1) collection of information input and output, a collection of elements type can be integers, real numbers or strings (2) determine the size of the collection (3) determine whether the collection is empty (4) The collection of blank (5) Find the specified element in the collection (6) to achieve pay collections, and , poor operation in the implementation process, the need to use object-oriented programming basics of the theory, which fully reflects the C++ language about classes, inheritance, encapsulation and polymorphism, and other core concepts, each class should contain data members and member functions.)