A PokerPlayer class derives virtually from the Person class. It has a Draw() member that returns a random number in the range 1 through 52, representing a card value. (Optionally, you could define a Card class with suit and face value members and use a Card return value for Draw().) The PokerPlayer class uses the Person show() function. The BadDude class derives publicly from the Gunslinger and PokerPlayer classes. It has a Gdraw() member that returns a bad dude’s draw time and a Cdraw() member that returns the next card drawn. It has an appropriate Show() function. Define all these classes and methods, along with any other necessary methods (such as methods for setting object values) and test them in a simple program similar to that in Listing 14.12.
5. Here are some class declarations:
// emp.h -- header file for abstr_emp class and children
#include
#include
class abstr_emp
{
private:
std::string fname; // abstr_emp's first name
std::string lname; // abstr_emp's last name
std::string job;
public:
abstr_emp();
abstr_emp(const std::string & fn, const std::string & ln,
const std::string & j);
virtual void ShowAll() const; // labels and shows all data
virtual void SetAll(); // prompts user for values
friend std::ostream &
operator<<(std::ostream & os, const abstr_emp & e);
// just displays first and last name
virtual ~abstr_emp() = 0; // virtual base class
};
class employee : public abstr_emp
{
public:
employee();
employee(const std::string & fn, const std::string & ln,
const std::string & j);
virtual void ShowAll() const;
virtual void SetAll();
};
class manager: virtual public abstr_emp
{
private:
int inchargeof; // number of abstr_emps managed
protected:
int InChargeOf() const { return inchargeof; } // output
int & InChargeOf(){ return inchargeof; } // input
public:
manager();
manager(const std::string & fn, const std::string & ln,
const std::string & j, int ico = 0);
manager(const abstr_emp & e, int ico);
manager(const manager & m);
virtual void ShowAll() const;
virtual void SetAll();
};
class fink: virtual public abstr_emp
{
private:
std::string reportsto; // to whom fink reports
protected:
const std::string ReportsTo() const { return reportsto; }
std::string & ReportsTo(){ return reportsto; }
public:
fink();
fink(const std::string & fn, const std::string & ln,
const std::string & j, const std::string & rpo);
fink(const abstr_emp & e, const std::string & rpo);
fink(const fink & e);
virtual void ShowAll() const;
virtual void SetAll();
};
class highfink: public manager, public fink // management fink
{
public:
highfink();
highfink(const std::string & fn, const std::string & ln,
const std::string & j, const std::string & rpo,
int ico);
highfink(const abstr_emp & e, const std::string & rpo, int ico);
highfink(const fink & f, int ico);
highfink(const manager & m, const std::string & rpo);
highfink(const highfink & h);
virtual void ShowAll() const;
virtual void SetAll();
};
Note that the class hierarchy uses MI with a virtual base class, so keep in mind the special rules for constructor initialization lists for that case. Also note the presence of some protected-access methods. This simplifies the code for some of the highfink methods. (Note, for example, that if highfink::ShowAll() simply calls fink::ShowAll() and manager::ShowAll(), it winds up calling abstr_emp::ShowAll() twice.) Provide the class method implementations and test the classes in a program. Here is a minimal test program:
// pe14-5.cpp
// useemp1.cpp -- using the abstr_emp classes
#include
using namespace std;
#include "emp.h"
int main(void)
{
employee em("Trip", "Harris", "Thumper");
cout << em << endl;
em.ShowAll();
manager ma("Amorphia", "Spindragon", "Nuancer", 5);
cout << ma << endl;
ma.ShowAll();
fink fi("Matt", "Oggs", "Oiler", "Juno Barr");
cout << fi << endl;
fi.ShowAll();
highfink hf(ma, "Curly Kew"); // recruitment?
hf.ShowAll();
cout << "Press a key for next phase:\n";
cin.get();
highfink hf2;
hf2.SetAll();
cout << "Using an abstr_emp * pointer:\n";
abstr_emp * tri[4] = {&em, &fi, &hf, &hf2};
for (int i = 0; i < 4; i++)
tri[i]->ShowAll();
return 0;
}
Why is no assignment operator defined?
Why are ShowAll() and SetAll() virtual?
Why is abstr_emp a virtual base class?
Why does the highfink class have no data section?
Why is only one version of operator<<() needed?
What would happen if the end of the program were replaced with this code?
abstr_emp tri[4] = {em, fi, hf, hf2};
for (int i = 0; i < 4; i++)
tri[i].ShowAll();
15. Friends, Exceptions, and More
In this chapter you’ll learn about the following:
• Friend classes
• Friend class methods
• Nested classes
• Throwing exceptions, try blocks, and catch blocks
• Exception classes
• Runtime type identification (RTTI)
• dynamic_cast and typeid
• static_cast, const_cast, and reinterpret_cast