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C++ Operator Overloading

Example of Operator Overloading in C++

C++ has the ability to provide the operators with a special meaning for a data type, this ability is known as operator overloading. Operator overloading is a compile-time polymorphism. For example, we can overload an operator ‘+’ in a class like String so that we can concatenate two strings by just using +. Other example classes where arithmetic operators may be overloaded are Complex Numbers, Fractional Numbers, Big integers, etc.

Example:

int a;
float b,sum;
sum = a + b;

Here, variables “a” and “b” are of types “int” and “float”, which are built-in data types. Hence the addition operator ‘+’ can easily add the contents of “a” and “b”. This is because the addition operator “+” is predefined to add variables of built-in data type only. 

Implementation:

C++




// C++ Program to Demonstrate the
// working/Logic behind Operator
// Overloading
class A {
    statements;
};
 
int main()
{
    A a1, a2, a3;
 
    a3 = a1 + a2;
 
    return 0;
}
 






                        









													
													
												

												
												

													
													
In this example, we have 3 variables “a1”, “a2” and “a3” of type “class A”. Here we are trying to add two objects “a1” and “a2”, which are of user-defined type i.e. of type “class A” using the “+” operator. This is not allowed, because the addition operator “+” is predefined to operate only on built-in data types. But here, “class A” is a user-defined type, so the compiler generates an error. This is where the concept of “Operator overloading” comes in.

													
													
												

												
												

													
													
Now, if the user wants to make the operator “+” add two class objects, the user has to redefine the meaning of the “+” operator such that it adds two class objects. This is done by using the concept of “Operator overloading”. So the main idea behind “Operator overloading” is to use C++ operators with class variables or class objects. Redefining the meaning of operators really does not change their original meaning; instead, they have been given additional meaning along with their existing ones.

													
													
												

												
											

											
											

												
Operator Overloading in C++

												
												

													
													
in C++, Operator overloading is a compile-time polymorphism. It is an idea of giving special meaning to an existing operator in C++ without changing its original meaning.

													
													
												

												
												

													
													
In this article, we will further discuss about operator overloading in C++ with examples and see which operators we can or cannot overload in C++.

													
													
												

												
											

										


										
										

											
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														C++ Operator Overloading

													

														C++ has the ability to provide the operators with a special meaning for a data type, this ability is known as operator overloading. Operator overloading is a compile-time polymorphism. For example, we can overload an operator ‘+’ in a class like String so that we can concatenate two strings by just using +. Other example classes where arithmetic operators may be overloaded are Complex Numbers, Fractional Numbers, Big integers, etc....
													

												
											

											
											

												
													

														Example of Operator Overloading in C++

													

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														Difference between Operator Functions and Normal Functions

													

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// C++ Program to Demonstrate
// Operator Overloading
#include 
using namespace std;
 
class Complex {
private:
    int real, imag;
 
public:
    Complex(int r = 0, int i = 0)
    {
        real = r;
        imag = i;
    }
 
    // This is automatically called when '+' is used with
    // between two Complex objects
    Complex operator+(Complex const& obj)
    {
        Complex res;
        res.real = real + obj.real;
        res.imag = imag + obj.imag;
        return res;
    }
    void print() { cout << real << " + i" << imag << '\n'; }
};
 
int main()
{
    Complex c1(10, 5), c2(2, 4);
    Complex c3 = c1 + c2;
    c3.print();
}...
													

												
											

											
											

												
													

														Can We Overload All Operators?

													

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														Operators that can be Overloaded in C++

													

														Operator functions are the same as normal functions. The only differences are, that the name of an operator function is always the operator keyword followed by the symbol of the operator, and operator functions are called when the corresponding operator is used....
													

												
											

											
											

												
													

														Why can’t the above-stated operators be overloaded?

													

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														Important Points about Operator Overloading

													

														Almost all operators can be overloaded except a few. Following is the list of operators that cannot be overloaded....
													

												
											

											
										


									

									

										
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												Example of Operator Overloading in C++