FRIEND FUNCTION IN C++

 #include<iostream>

using namespace std;

class cl

{

int a;

public:

void input(int x)

{

a=x;

}

void output()

{

cout<<a<<endl;

}

friend void f(cl ); // the function f() is a friend function , which can access the private member of class cl.

};

// The functiin f is not a member function of f(cl ) . For this reason no scope resolution operator is used .

void f(cl ob)

{

cout<<ob.a<<endl; // ob.a is a private member of class cl.

}

int main ()

{

cl ob;

cout<<"sunday"<<endl;

ob.input(100);

cout<<"monday"<<endl;

ob.output();

cout<<"friday"<<endl;

f(ob);

}

DESTRUCTOR IN C++ (2)

 #include<iostream>

using namespace std;

class cl

{

int a;

public:

  cl();

  cl(int x);

  void output();

  ~cl();

};

cl::cl()

{

a=10;

cout<<"overloading"<<a<<endl;

}

cl::cl(int x)

{

a=x;

cout<<"overloading"<<a<<endl;

}

void cl::output()

{

cout<<a<<endl;

}

cl::~cl()

{

cout<<"destructing"<<a<<endl;

}

void f( cl ob3)

{

cout<<"monday"<<endl;

}

int main()

{

cl ob(100),ob1,ob2(50),ob3(30);

cout<<"sunday"<<endl;

f(ob3);

cout<<"friday"<<endl;

}

DESTRUCTOR IN C++ (1)

 #include<iostream>

using namespace std;

class cl

{

int a;

public:

  cl();

  cl(int x);

  void output();

  ~cl();

};

cl::cl()

{

a=10;

cout<<"overloading"<<a<<endl;

}

cl::cl(int x)

{

a=x;

cout<<"overloading"<<a<<endl;

}

void cl::output()

{

cout<<a<<endl;

}

cl::~cl()

{

cout<<"destructing"<<a<<endl;

}

int main()

{

cl ob,ob1(20),ob2(30);

cout<<"sunday"<<endl;

}

COPY CONSTRUCTOR IN C++

 #include<iostream>

using namespace std;

class cl

{

int a;

public:

  cl();

  cl(int x);

  cl(cl &ob); //copy constructor

  void output();

  ~cl();

};

cl::cl()

{

a=10;

cout<<"overloading"<<a<<endl;

}

cl::cl(int x)

{

a=x;

cout<<"overloading"<<a<<endl;

}

void cl::output()

{

cout<<a<<endl;

}

cl::~cl()

{

cout<<"destructing"<<a<<endl;

}

void f( cl ob3)

{

cout<<"monday"<<endl;

}

cl::cl(cl &ob)

{

a=ob.a;

cout<<"copy constructor"<<a<<endl;

}

int main()

{

cl ob(100),ob1,ob2(50),ob3(30);

cout<<"sunday"<<endl;

f(ob3);

cout<<"friday"<<endl;

cl ob4(500); // parameterised constructor

cl ob5=ob4; // copy constructor

cl ob6(ob); // copy constructor

}

DIVISION OF TWO COMPLEX NUMBER USING FRIEND FUNCTION

 #include<iostream>

using namespace std;

class complex

{

int a,b;

public:

complex()

{

}

complex(int x,int y)

{

a=x;

b=y;

}

void display()

{

if(b>0)

{

cout<<a<<"+i"<<b<<endl;

}

else

{

cout<<a<<"-i"<<b<<endl;

}

}

friend void add(complex,complex);

};

void add(complex ob1, complex ob2)

{

complex ob3;

ob3.a=ob1.a/ob2.a;

ob3.b=ob1.b/ob2.b;

ob3.display();

}

int main()

{

complex ob1(2,-3),ob2(4,5);

add(ob1,ob2);

}

MULTIPLICATION OF TWO COMPLEX NUMBER USING FRIEND FUNCTION

 #include<iostream>

using namespace std;

class complex

{

int a,b;

public:

complex()

{

}

complex(int x,int y)

{

a=x;

b=y;

}

void display()

{

if(b>0)

{

cout<<a<<"+i"<<b<<endl;

}

else

{

cout<<a<<"-i"<<b<<endl;

}

}

friend void add(complex,complex);

};

void add(complex ob1, complex ob2)

{

complex ob3;

ob3.a=ob1.a*ob2.a;

ob3.b=ob1.b*ob2.b;

ob3.display();

}

int main()

{

complex ob1(2,-3),ob2(4,5);

add(ob1,ob2);

}

SUBTRACTION OF TWO COMPLEX NUMBER USING FRIEND FUNCTION

 #include<iostream>

using namespace std;

class complex

{

int a,b;

public:

complex()

{

}

complex(int x,int y)

{

a=x;

b=y;

}

void display()

{

if(b>0)

{

cout<<a<<"+i"<<b<<endl;

}

else

{

cout<<a<<"-i"<<b<<endl;

}

}

friend void add(complex,complex);

};

void add(complex ob1, complex ob2)

{

complex ob3;

ob3.a=ob1.a-ob2.a;

ob3.b=ob1.b-ob2.b;

ob3.display();

}

int main()

{

complex ob1(2,-3),ob2(4,5);

add(ob1,ob2);

}