1. Introduction Rules Types Programs
OPERATOR OVERLOADING
Introduction
Rules
Types
Programs

2. Introduction
Allows us to define the behavior of operators when applied to objects of a class
Operator Overloading does not allow us to alter the meaning of operators when applied to built-in types
Example: addition, 2*3 multiplication
By operator overloading, we can apply the operators to our own abstract data type like this
Example;
Class A{
int a,b;
public:
A(int x,int y){a=x;b=y;} };
main() {
A obj1(2,3);
-obj1; }

3. To Overload an Operator
Steps
Overloading an operator
Write function definition as normal
Function name : operator keyword followed by the symbol
Operator+ ()
Applying operators on objects
Create objects for the class
Apply the operator on objects
object1 + object2
-object1

4. Rules to Overload an operator
Precedence of an operator cannot be changed
Associativity of an operator cannot be changed
Arity (number of operands) cannot be changed
No new operators can be created ( Ex: +-)
Use only existing operators
No overloading operators for built-in types
Cannot change how two integers are added
Produces a syntax error (Ex; 2+3)
Operator functions can be member or non- member functions

5. Rules to Overloade an operator
C++ operators that can be overloaded
C++ Operators that cannot be overloaded

6. Types Syntax Return type class name :: operator symbol(args){ }
Using Member Function
Unary Operator Overloading
Ex: A operator –() ( )
Binary Operator Overloading
Ex: A operator –(A object) ( )
Using Non Member Function (use Friend Keyword)
Ex: A operator –(A object1, A object2) ( )

7. Unary operator : Member Function
class A
{ int inches,feet;
public:
A(int x,int y) { inches=x; feet=y; }
void display()
{ cout <<"\n"<<inches<<" "<<feet;}
void operator-()
{ inches=-inches; feet=-feet; } };
int main() {
A obj1(20,10);
obj1.display();
-obj1; }

8. Binary operator Using Member Function
class A {
int a,b;
public:
A(int x,int y)
{ a=x; b=y; }
void display()
{ cout <<"\n"<<inches<<" "<<feet;}
void operator+(A o1); };
Void A :: operator +(A o1)
a=a+o1.a;
b=b+o1.b; }

9. int main() { A obj1(20,10); A. obj2(10,20); obj1+obj2; obj1
int main() { A obj1(20,10); A.obj2(10,20); obj1+obj2; obj1.display(); }

10. Unary operator : Non Member Function class A { int a,b public: A() { a=b=0; } A(int x,int y) { a=x; b =y; } void display() { cout <<"\n"<<a<<" "<<b;} friend A operator-(A) }; A operator-(A d1) A d2; d2.a=-d1.a; d2.b=-d1.b; return d2; } ;

11. int main() {
A obj1(20,10);
obj1.display();
A C;
C=-obj1;
C.display(); }

12. Unary operator : Non Member Function class A { int a,b public: A() { a=b=0; } A(int x,int y) { a=x; b =y; } void display() { cout <<"\n"<<a<<" "<<b;} friend A operator+(A,A) }; A operator+(A d1,A d2) A d3; d3.a=-d1.a+d2.a; d3.b=-d1.b+d2.b; return d3; } ;

13. int main() {
A obj1(20,10);
A obj2(20,10);
obj1.display();
Obj2.display();
A C;
C=obj1+obj2;
C.display(); }