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Object Orientedj
Programming using C++
Lecture – 11
Operator Overloading Continued
Operator Overloading
So far, we have used operator overloading to re-define
the built-in operations of the language for user definedthe built in operations of the language for user defined
data types
For this, the overloaded operators are made member
functions of a class
E.g., class complex_number {
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private: //private data public: complex_number operator + (const complex_number& number); };
Operator Overloading (contd..)
This, however, may not be applicable when the object
its self has to be passed as an argument to the operatorits self has to be passed as an argument to the operator
function
E.g., complex_number N1; cout<<N1; The compiler will interpret it as cout.operator<<(N1)
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cout is an object of the class ostream in C++.
Therefore, to print complex_number in our case the
insertion operator (<<) in class ostream has to be
overloaded. Bit cumbersome!
Overloading using Friends
Solution: Friend function
(We’ll come to the insertion operator overloading later!)(We ll come to the insertion operator overloading later!)
E.g.,
class complex_number { private: //private data
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public: friend complex_number operator + (complex_number& number1, complex_number& number2 ); };
Overloading I/O
Extraction:
int a;int a;
cin>>a;
//compiler’s interpretation
//cin.operator>>(a);
Insertion:
double b;
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double b;
cout<<b;
//compiler’s interpretation
//cout.operator<<(b);
Overloading I/O (contd..)
Example: class complex numberp _ { private: double real_part; double imag_part;
public: complex number(double a double b): real part(a) imag part(b)
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complex_number(double a, double b): real_part(a), imag_part(b) { } friend void operator>>(istream& in, complex_number& N); friend void operator<<(ostream& out, complex_number& N); };
Overloading I/O (contd..)
void operator>>(istream& in, complex_number& N) { cout<<“Enter a complex number (real part, imaginary part) : ”; cout<<endl;
in>>N.real_part>>N.imag_part; }
void operator<<(ostream& out, complex_number& N)
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p ( , p _ ) { out<<“Complex number is : ”<<endl <<N.real_part<<“ + i”<<N.imag_part<<endl; }
Overloading I/O (contd..)
void main() {{ complex_number cNumber;
cin>>cNumber; //compiler’s interpretation is //operator>>(cin, cNumber);
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cout<<cNumber; //compiler’s interpretation is //operator<<(cout, cNumber); }
