operator overloading using friend function

operator overloading both unary and binary operator using friend function.

What is a friend function c plus plus?

A friend function in C++ is a function that is not part of the implementation of a class, i.e. not a method of the class, but that is allowed to manipulate the private parts of a class.

#include <iostream>
using namespace std;
class loc {
int longitude, latitude;
public:
loc() {} // needed to construct temporaries
loc(int lg, int lt) {
longitude = lg;
latitude = lt;
}
void show() {
cout << longitude << " ";
cout << latitude << "\n";
}
friend loc operator+(loc , loc ); // now a friend
loc operator-(loc op2);
loc operator=(loc op2);
loc operator++();
};
// Now, + is overloaded using friend function.
loc operator+(loc op1, loc op2)
{
loc temp;
temp.longitude = op1.longitude + op2.longitude;
temp.latitude = op1.latitude + op2.latitude;
return *this;
}
// Overload - for loc.
loc loc::operator-(loc op2)
{
loc temp;
// notice order of operands
temp.longitude = longitude - op2.longitude;
temp.latitude = latitude - op2.latitude;
return temp;
}
// Overload assignment for loc
loc loc::operator=(loc op2)
{
longitude = op2.longitude;
latitude = op2.latitude;
return *this; // i.e., return object that generated call
}
// Overload ++ for loc.
loc loc::operator++()
{
longitude++;
latitude++;
return *this;
}
int main()
{
loc ob1(10, 20), ob2( 5, 30);
ob1 = ob1 + ob2;
ob1.show();
return 0;
}

C++ Operator Overloading Guidelines

One of the nice features of C++ is that you can give special meanings to operators, when they are used with user-defined classes. This is called operator overloading. You can implement C++ operator overloads by providing special member-functions on your classes that follow a particular naming convention. For example, to overload the + operator for your class, you would provide a member-function named operator+ on your class.
The following set of operators is commonly overloaded for user-defined classes:

• = (assignment operator)
• + - * (binary arithmetic operators)
• += -= *= (compound assignment operators)
• == != (comparison operators)