C++ Operator Overloading
Operator overloading means use of existing operators and perform a new task according to user-defined action.
We can overload all the CPP operators except the following:
- Scope resolution operators (::)
- Dot operator (.)
- Sizeof operator
- Conditional Operator or Ternary Operator (? :)
- New operator
Rules for Overloading Operators:
- Only Existing Operator can be overloaded.
- The overloaded operator must have at least one operand.
Operator overloading is defined like a function but with a operator keyword followed by a operator which you want to overload.
Types of Operator Overloading:
- Unary Operator Overloading
- Binary Operator Overloading
Unary operator
Unary operator works on just one operand. It takes no argument in the function definition. Unary operators are minus(-), increment(++), decrement(--)
Example 1: Input number and reverse the sign (if positive convert into negative, if negative convert into positive) using unary operator overload.
#include<iostream.h>
#include<conio.h>
class unary
{
int a;
public:
void input();
void output();
operator -() // unary operator defination
{
a=-a;
}
};
void unary::input()
{
cout<<"Enter Number: ";
cin>>a;
}
void unary::output()
{
cout<<"Value = "<<a;
}
int main()
{
unary obj1;
obj1.input();
-obj1; //operator minus(-) call
obj1.output();
return 0;
}
Enter number: 25
Value = -25
Run 2:
Enter number: -15
Value = 15
Binary operator
Binary Operator works on two operands. It takes only one argument in the function definition.
//calling syntax:
c3=c1+c2
or
c3=c1.operator+(c2)
Example 2: Input 2 numbers and find sum using binary operator overload.
class binary
{
int a;
public:
void input();
void output();
binary operator+(binary obj2){
binary obj3;
obj3.a = a + obj2.a;
return obj3;
}
};
void binary::input()
{
cout<<"Enter number: ";
cin>>a;
}
void binary::output()
{
cout<<"Result = "<<a;
}
int main()
{
binary obj1, obj2, obj3;
clrscr();
obj1.input();
obj2.input();
obj3 = obj1 + obj2; // operator overloading call
obj3.output();
getch();
}
Enter number: 20
Result = 30
Binary Operator Overloading using Friend keyword
Operator overloading can be use using friend keyword. The only difference is that a friend opertor overloading requires two arguments in the operator definition.
//calling syntax:
c3=c1+c2
or
c3=operator+(c1,c2)
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