How to pass and return object from a function in C++?

In this article, you will learn to pass objects to a function and return object from a function in C++ programming.
Pass and  return object from function in C++

In C++ programming, objects can be passed to a function in a similar way as structures.


How to pass objects to a function?

Pass Object to a function in C++


Example 1: Pass Objects to Function

C++ program to add two complex numbers by passing objects to a function.

#include <iostream>
using namespace std;

class Complex
{
    private:
       int real;
       int imag;
    public:
       Complex(): real(0), imag(0) { }
       void readData()
        {
           cout << "Enter real and imaginary number respectively:"<<endl;
           cin >> real >> imag;
        }
        void addComplexNumbers(Complex comp1, Complex comp2)
        {
           // real represents the real data of object c3 because this function is called using code c3.add(c1,c2);
            real=comp1.real+comp2.real;

             // imag represents the imag data of object c3 because this function is called using code c3.add(c1,c2);
            imag=comp1.imag+comp2.imag;
        }

        void displaySum()
        {
            cout << "Sum = " << real<< "+" << imag << "i";
        }
};
int main()
{
    Complex c1,c2,c3;

    c1.readData();
    c2.readData();

    c3.addComplexNumbers(c1, c2);
    c3.displaySum();

    return 0;
}

Output

Enter real and imaginary number respectively:
2
4
Enter real and imaginary number respectively:
-3
4
Sum = -1+8i

How to return an object from the function?

In C++ programming, object can be returned from a function in a similar way as structures.


Return object from a function in C++


Example 2: Pass and Return Object from the Function

In this program, the sum of complex numbers (object) is returned to the main() function and displayed.

#include <iostream>
using namespace std;
class Complex
{
    private:
       int real;
       int imag;
    public:
       Complex(): real(0), imag(0) { }
       void readData()
        {
           cout << "Enter real and imaginary number respectively:"<<endl;
           cin >> real >> imag;
        }
        Complex addComplexNumbers(Complex comp2)
        {
            Complex temp;

            // real represents the real data of object c3 because this function is called using code c3.add(c1,c2);
            temp.real = real+comp2.real;

            // imag represents the imag data of object c3 because this function is called using code c3.add(c1,c2);
            temp.imag = imag+comp2.imag;
            return temp;
        }
        void displayData()
        {
            cout << "Sum = " << real << "+" << imag << "i";
        }
};

int main()
{
    Complex c1, c2, c3;

    c1.readData();
    c2.readData();

    c3 = c1.addComplexNumbers(c2);

    c3.displayData();
    
    return 0;
}