继承，运算符重载，类，Date类 栈类，三角形类Triangle-Inheritance, operator overloading, Class, Date Class stack type, triangle-type Triangle

编写类student，其中包含生日（年、月、日）的私有变量，要求能比较两位学生的年龄差距（精确到多少天），用重载“－”运算符实现年龄差的计算-Writing class student, which includes birth (year, month, day) of the private variables, two students asked to compare the age difference (accurate to the number of days), with a

实现复数的运算，主要通过运算符及输入输出重载-implement the manipulation of complex