Operator Overloading in C++
1. When an operator is overloaded with multiple jobs, it is known as operator overloading.
2. Operator overloading is a way to implement compile time polymorphism.
3. Any symbol can be used as function name if
(a.) if it is a valid operator in C language.
(b.) if it is preceded by operator keyword.
4. We cannot overload sizeof operator and ternary (?:) operator.
For Example:-
#include<iostream>
using namespace std;
class Complex
{
private:
int real, imaginary;
public:
void setData(int num1, int num2)
{
real = num1;
imaginary = num2;
}
void showData()
{
cout << real << " " << imaginary;
}
Complex operator+(Complex C) //operator overloading of + symbol.
{
Complex temp;
temp.real = real+C.real;
temp.imaginary = imaginary+C.imaginary;
return temp;
}
};
int main()
{
Complex C1,C2,C3;
C1.setData(3,4);
C2.setData(5,6);
C3 = C1+C2; //calling operator overloading.
C3.showData();
}Output:
8 10
Overloading of Unary Operator
Operator which takes only one operand to perform operation is called unary operator. To know more about different types of operator, you should check this >> Operators
Unary operator can be overloaded as follows.
For Example:-
#include<iostream>
using namespace std;
class Complex
{
private:
int real, imaginary;
public:
void setData(int num1, int num2)
{
real = num1;
imaginary = num2;
}
void showData()
{
cout<< real << " " << imaginary;
}
Complex operator-() //operator overloading of unary operator -.
{
Complex temp;
temp.real = -real;
temp.imaginary = -imaginary;
return temp;
}
};
int main()
{
Complex C1,C2;
C1.setData(9,2);
C2 = -C1; //C2=c1.operator-() calling unary operator overloading.
C2.showData();
}Output:
-9 -2
Pre and Post increment Operator Overloading
The symbol of prefix (++i) and postfix (i++) operator is same so we need to use a dummy int as parameter in postfix version to distinguish between the two functions definition.
For Example:-
#include<iostream>
using namespace std;
class Integer
{
private:
int num;
public:
void setData(int a)
{
num = a;
}
void showData()
{
cout << "\n integer is: "<< num;
}
Integer operator++() //preincrement operator overloading.
{
Integer i;
i.num = ++num;
return i;
}
Integer operator++(int) //postincrement operator overloading.
{
Integer i;
i.num = num++;
return i;
}
};
int main()
{
Integer i1, i2;
i1.setData(55);
i1.showData();
i2 = i1++; //i2=i1.operator++()
i2.showData();
i2 = ++i1;
i2.showData();
}Output:
integer is: 55 integer is: 55 integer is: 57
For more information: Operator overloading as a friend function, overloading of unary operator as a friend function, insertion and extraction operator overloading.
Read Here >> More on Operator Overloading