OOP 5th ass

#include<iostream>
using namespace std;

class complex{
public:
    float real,imag;
    complex(){
        real=0;
        imag=0;
    }
    complex operator +(complex);
    complex operator -(complex);
    complex operator *(complex);
    complex operator /(complex);
    friend ostream &operator <<(ostream &output,complex &t)
    {
        output<<t.real<<"+"<<t.imag<<"i\n";
        return output;
    }
    friend istream &operator >>(istream &input,complex &nn)
    {
    cout<<"Enter the real part:";
    input>>nn.real;
    cout<<"Enter the imaginary part";
    input>>nn.imag;
    return input;
    }
};

complex complex::operator +(complex n2){
    complex n3;
    n3.real=real+n2.real;
    n3.imag=imag+n2.imag;
    return(n3);
}
complex complex::operator -(complex n2){
    complex n3;
    n3.real=real-n2.real;
    n3.imag=imag-n2.imag;
    return n3;
}
complex complex::operator *(complex n2){
    complex n4;
    n4.real=(real*n2.real)-(imag*n2.imag);
    n4.imag=(imag*n2.real)+(real*n2.imag);
    return (n4);
}
complex complex::operator /(complex n2){
    complex n3;
    int temp=n2.real*n2.real+n2.imag*n2.imag;
    n3.real=(real*n2.real+n2.imag*imag)/temp;
    n3.imag=(imag*n2.real-n2.imag*real)/temp;
    return n3;
}
int main(){
    complex c1,c2,c3,c4,c5,c6;
     cout<<"Default constructor value=\n";
     int ch=10;
     cout<<c1;
    do{
        cout<<"Enter 1 to calculate sum of complex number\n";
        cout<<"Enter 2 to calculate difference of complex numbers\n";
        cout<<"Enter 3 to calculate multiplication of two complex numbers\n";
        cout<<"Enter 4 to calculate division of two complex numbers\n";
        cout<<"Enter 0 to exit\n";
        cout<<"Enter your choice:\n";
        cin>>ch;
        switch(ch){
        case 1:
            cout<<"Enter the details for first number\n";
            cin>>c1;
            cout<<"Enter the details for second number\n";
            cin>>c2;
            c3=c1+c2;
            cout<<c3;
            break;
        case 2:
            cout<<"Enter the details for first number\n";
            cin>>c1;
            cout<<"Enter the details for second number\n";
            cin>>c2;
            c3=c1-c2;
            cout<<"Subtraction of "<<c1<<" and "<<c2<<" is "<<c3;
            break;
        case 3:
            cout<<"Enter the details for first number\n";
            cin>>c1;
            cout<<"Enter the details for second number\n";
            cin>>c2;
            c3=c1*c2;
            cout<<c3;
            break;
        case 4:
            cout<<"Enter the details for first number\n";
            cin>>c1;
            cout<<"Enter the details for second number\n";
            cin>>c2;
            c3=c1/c2;
            cout<<c3;
            break;
        default:
            cout<<"Enter proper choice!!"<<endl;
            break;
        }
    }while(ch!=0);
    return 0;
}