#include<iostream>
using namespace std;

class Complex
{
private:
    int a,b;
public:
    Complex(int a1,int b1=0):a(a1),b(b1){};
    ~Complex(){};
    void jiaf(const Complex &copy)
    {
        a+=copy.a;
        b+=copy.b;
    }
    void jianf(const Complex &copy)
    {
        a-=copy.a;
        b-=copy.b;
    }
    void chengf(const Complex &copy)
    {
        int c=a;
        a=a*copy.a-b*copy.b;
        b=c*copy.b+b*copy.a;
    }
    void chuf(const Complex &copy)
    {
        int d;
        b=-b;
        d=-copy.b;
        int c=a;
        a=a*copy.a-b*d;
        b=c*d+b*copy.a;
    }
    void Show()
    {
        if(b>0)
            cout<<a<<"+"<<b<<endl;
        else if(b==0)
        {
            cout<<a<<endl;
        }
        else
            cout<<a<<b<<endl;
    }
};
int main()
{
    void Show1();
    char c;
   
    do
    {
        cout<<"输入一个复数："<<endl;
        int a1,b1;
        cin>>a1>>b1;
        Complex p1(a1,b1);

        cout<<"输入一个复数："<<endl;
        int a2,b2;
        cin>>a2>>b2;
        Complex p2(a2,b2);

        Show1();
        int a;
        cin>>a;
        if(a==5)
        {
            
            exit(1);
        }
        while(a!=1&&a!=2&&a!=3&&a!=4&&a!=4)
        {
            Show1();
            cout<<"重新输入a"<<endl;
            cin>>a;
        }
        switch(a)
        {
        case 1:
            p1.jiaf(p2);
        case 2:
            p1.jianf(p2);
        case 3:
            p1.chengf(p2);
        case 4:
            p1.chuf(p2);
        }
        cout<<"结果是："<<endl;
        p1.Show();
        cout<<"是否继续？（Y/N）"<<endl;
   
        cin>>c;
    }while(c=='y'||c=='Y');
}
void Show1()
{
    cout<<"进行复数的运算  "<<endl;
    cout<<"1  +  "<<endl;
    cout<<"2  -"<<endl;
    cout<<"3  * "<<endl;
    cout<<"4  /"<<endl;
    cout<<"5  退出"<<endl;
    cout<<"输入数字编码"<<endl;
}

a+=copy.a; copy 是什么

看错了，case后面忘了break；

谢谢了，虽然我已经找到错误