תכנות מונחה עצמים

Emploee E;

Manager M;

M.is_manager_of(E)      // Type of this is Manager*,

                  // No casting occurs

M.raise_salary(10);     // Type of this is Employee*

                  // in raise_salary.

                  // Up casting must occur

Employee  E, *pE;

Manager   M, *pM;

pE = &M;                // OK: implicit upcasting.

M = *pE;                // Error: implicit downcasting is not allowed

// explicit down casting:

M = *(Manager *)pE;                 // deprecated syntax

M = *static_cast<Manager*>pE;       // recommended syntax

Manager &mRef = dynamic_cast<Manager &>eRef;

#include <iostream>

#include <cstdlib>

using namespace std;

class A

{

public:

    virtual void f() {};

};

class B : public A

{

public:

    void f() {};

};

class C

{

public:

    void f() {};  

};

int main()

{

      A *a1 = new A;

      A *b1 = new B;

      C *c1 = new C;

      if (B* ref1 = dynamic_cast<B*>(b1))

            cout << "b1 is B" << endl;

      else

            cout << "b1 isn't B" << endl;

      if (C* ref1 = dynamic_cast<C*>(b1))

            cout << "b1 is C" << endl;

      else

            cout << "b1 isn't C" << endl;

      return 0;

}

b1 is B

b1 isn't C