Function Overloading Can enables several function Of same name Of different sets of parameters (at least as far as their types are concerned) Used to create several functions of the same name that perform similar tasks but on different data types

Square function int square(int x) { return x*x; } double square(double y) { return y*y;} float square(float z) { return z*z;}

Use overloaded function Complier will search for the match function prototype int main() { int x=7; double y=7.5; cout<<“square of “<<x<<“ is “ <<square(x)<<endl; cout<<“Square of “<<y<<“is “ <<square(y)<<endl; }

Friend function and friend class A friend function of a class is defined outside that class scope Has right to access private members of the class Using friend functions can enhance performance Often appropriate when a member function cannot be used for certain operations

Declare a function as friend To declare a function as a friend of a class, precede the function prototype in class definition with key word friend To declare a class Two as a friend of One, place friend class Two; in the definition of class One

Friendship Friendship is granted, not taken Friendship is not symmetric If B is friend of A, I.e. A declared B as friend, you cannot infer A is friend of B unless B declare A as friend Friendship is not transitive A is friend of B, and B is friend of C, you cannot say that A is friend of C

Example class Count { friend void setX(Count &, int); public: Count(){x=0;} void print() const {cout<<x<<endl;} private: int x; };

Example continue void setX(Count &c, int val) { c.x = val; } int main() { Count counter; counter.print(); setX(counter, 8); return 0; }

Use this pointer Every object has access to its own address through a pointer called this This pointer is not part of object This pointer is passed into object (by compiler) as implicit first argument on every non-static member function

class Test { int x; public: Test( int =0); void print() const; }; Test::test(int a){ x = a;} void Test::print() const { cout<<“ x = “<<x x = “ x <<“\n(*this).x = “<<(*this).x <<endl; }

int main() { Test t(12); t.print(); return 0; } x = 12 this->x = 12 (*this).x = 12 Output:

Operator Overloading Enable C++’s operators to work with class object >, +, -, *, / This operators perform differently depending on their context in integer, floating These operators are overloaded C++ allow programmer to overload most operators

Can we make Complex class easier to use as follow? int main() { Complex x,y,z; cout<<“Type in two complex numbers\n”; cin>>x >>y; z = x + y; cout<< x <<“+” <<y<<“=“ <<z<<endl; } Type in two complex numbers (2,3) (3,4) (2,3) + (3,4) = (5,7)

Yes, Overload the operators Operator are overloaded by writing a function definition( header and body) Function name become the keyword operator followed by the symbol for the operator being overloaded operator+ would be used to overload the addition operator(+) Precedence and associativity of an operator cannot be changed by overloading

Where to define overloading operator As non member function Must be friend of the class So it is in class definition class Complex { friend ostream& operator<< (ostream&, const Complex &);... } Function name Return type parameters

Implementation ostream & operator<<(ostream & out, const Complex &c) { out<<“(“<<c.real<<“,”<<c.img<<“)”; return out; // enables cout<<x<<y; }

Overload operator >> In class definition class Complex { friend ostream& operator<< (ostream &, const Complex &); friend istream& operator>> (istream&, Complex &);... }

implementation istream & operator>>( istream & input,Complex & c) { input.ignore(); input>>c.real; input.ignore(); input>>c.img; input.ignore(); return input; }