实验七-运算符重载参考答案

1、 实验七 多态性函数与运算符重载7.1 实验目的1理解掌握成员函数方式运算符重载；2理解掌握友元函数方式运算符重载；3理解掌握+、-运算符的重载。7.2 实验内容7.2.1程序阅读1理解下面的程序，并运行查看结果，回答程序后面的问题。#include <iostream>using namespace std;class CComplexpublic:CComplex()real = 0; imag = 0;CComplex(int x,int y)real = x;imag = y;int real;int imag;CComplex operator + (CComplex o

2、bj1)/-CComplex obj2(real - obj1.real, imag - obj1.imag);return obj2;int main()CComplex obj1(100,30);CComplex obj2(20, 30);CComplex obj;obj = obj1+obj2; /-cout << obj.real <<endl;cout << obj.imag << endl;return 0;问题一：处的运算符重载，为什么该函数的返回值要设计成CComplex类型？答：因为在函数中return obj2,obj2是CC

3、omplex类型，所以函数返回值要与return返回的类型相同，即设计成CComplex类型。问题二：处的运算符重载函数调用就相当于“obj=operator+(obj1,obj2);”，但是为什么CComplex类中的运算符重载函数只设计了一个参数？答：因为成员函数经编译后会产生this指针， this指针会指向调用该函数的obj1对象，该obj1对象就是就相当于函数的第一个参数。因此可以在函数参数列表中只设计一个参数。问题三：上述程序设计合理吗？为什么？答：不合理，因为它所实现的功能是obj2-obj1，而重载运算符的名字为“+”，这使用起来非常不直观，会让人以为这实现的功能是obj1+o

4、bj2。2理解下面的程序，并运行查看结果，回答程序后面的问题。#include <iostream>using namespace std;class CComplexpublic:CComplex()real = 0.0; imag = 0.0;CComplex(float x, float y)real = x;imag = y;CComplex operator + (CComplex &obj1, CComplex &obj2)CComplex obj3(obj1.real + obj2.real, obj1.imag + obj2.imag);return

5、 obj3;CComplex &operator+(CComplex &obj)/重载前置自增运算符+obj.real;+obj.imag ;return obj;void print()cout<<real<<"+"<<imag<<"i"<<endl;private:float real;float imag;CComplex &operator-(CComplex &x) /重载前置自减运算符-x.real;-x.imag;return x;int main(

6、)CComplex obj1(2.1,3.2);CComplex obj2(3.6,2.5);cout<<"obj1="obj1.print();cout<<"obj2="obj2.print();CComplex obj3 = obj1 + obj2;cout<<"before+, obj3="obj3.print();+obj3;cout<<"after+, obj3="obj3.print();-obj3;cout<<"after-, ob

7、j3="obj3.print();CComplex obj4 = +obj3;cout<<"obj4="obj4.print();return 0;问题一：以上程序中的三个运算符重载都有错误，试改正过来，使程序输出正确结果。答：1.两个复数相加l 修改方案一：将CComplex operator + (CComplex &obj1, CComplex &obj2);定义为友元函数在类体外写。l 修改方案二：将CComplex operator + (CComplex &obj1, CComplex &obj2);的形参改

8、为一个，写在类体中，哪个对象调用，即对其与另一个对象进行运算符操作。2.前置自增修改方案：重置自增运算符，设置无形参的重载函数，对所使用的对象进行自增，在通过return *this返回该对象。3.前置自减修改方案：忘记在类中声明为友元函数。正确代码：#include <iostream>using namespace std;class CComplexpublic:CComplex()real = 0.0;imag = 0.0;CComplex(float x, float y)real = x;imag = y;CComplex operator + (CComplex &a

9、mp;obj2)/1CComplex obj3(real + obj2.real, imag + obj2.imag);return obj3;CComplex &operator+()/重载前置自增运算符/2+real;+imag ;return *this;void print()cout<<real<<"+"<<imag<<"i"<<endl;friend CComplex &operator-(CComplex &x);/3private:float real;f

10、loat imag;CComplex &operator-(CComplex &x) /重载前置自减运算符-x.real;-x.imag;return x;int main()CComplex obj1(2.1,3.2);CComplex obj2(3.6,2.5);cout<<"obj1="obj1.print();cout<<"obj2="obj2.print();CComplex obj3 = obj1 + obj2;cout<<"before+, obj3="obj3.pri

11、nt();+obj3;cout<<"after+, obj3="obj3.print();-obj3;cout<<"after-, obj3="obj3.print();CComplex obj4 = +obj3;cout<<"obj4="obj4.print();return 0;7.2.2 程序设计1把7.2.1中第二道题的程序改造成能实现复数的减法、乘法、除法以及后置“+”、“-”运算，并设计主函数来验证重载运算符的用法。#include <iostream>using names

12、pace std;class CComplexpublic:CComplex()real = 0.0;imag = 0.0;CComplex(float x, float y)real = x;imag = y;CComplex operator - (CComplex &obj2)CComplex obj3(real - obj2.real, imag - obj2.imag);return obj3;CComplex operator+(int)/重载后置自增运算符CComplex temp(*this); real+; imag+; return temp; CComplex o

13、perator-(int) /重载后置自减运算符 CComplex temp(*this); real-; imag-; return temp; void print() if(imag>=0)cout<<real<<"+"<<imag<<"i"<<endl;else cout<<real<<imag<<"i"<<endl;friend CComplex operator * (CComplex &obj1, C

14、Complex &obj2);/两个复数相乘friend CComplex operator / (CComplex &obj1, CComplex &obj2);/两个复数相除private:float real;float imag;CComplex operator * (CComplex &obj1, CComplex &obj2) return CComplex(obj1.real*obj2.real-obj1.imag*obj2.imag),(obj1.imag*obj2.real+obj1.real*obj2.imag);CComplex

15、operator / (CComplex &obj1, CComplex &obj2) return CComplex(obj1.real*obj2.real+obj1.imag*obj2.imag)/(obj2.real*obj2.real+obj2.imag*obj2.imag),(obj1.imag*obj2.real-obj1.real*obj2.imag)/(obj2.real*obj2.real+obj2.imag*obj2.imag);int main()CComplex obj1(3,-1);CComplex obj2(2,-1);cout<<"obj1="obj1.print();cout<<"obj2="obj2.print(); cout<<"obj1*obj2="CComplex obj3=obj1*obj2;obj3.print(); cout<<"obj1/obj2="CComplex obj4=obj1/obj2;obj4.pr