1   // Fig. 7.9: employ1.h
2   // An employee class
3   #ifndef EMPLOY1_H
4   #define EMPLOY1_H
5   
6   class Employee {
7   public:
8      Employee( const char*, const char* );  // constructor
9      ~Employee();                       // destructor
10     const char *getFirstName() const;  // return first name
11     const char *getLastName() const;   // return last name
12  
13     // static member function
14     static int getCount();  // return # objects instantiated
15  
16  private:
17     char *firstName;
18     char *lastName;
19  
20     // static data member
21     static int count;  // number of objects instantiated
22  };
23  
24  #endif
25  // Fig. 7.9: employ1.cpp
26  // Member function definitions for class Employee
27  #include <iostream.h>
28  #include <string.h>
29  #include <assert.h>
30  #include "employ1.h"
31  
32  // Initialize the static data member
33  int Employee::count = 0;
34  
35  // Define the static member function that
36  // returns the number of employee objects instantiated.
37  int Employee::getCount() { return count; }
38  
39  // Constructor dynamically allocates space for the
40  // first and last name and uses strcpy to copy
41  // the first and last names into the object
42  Employee::Employee( const char *first, const char *last )
43  {
44     firstName = new char[ strlen( first ) + 1 ];
45     assert( firstName != 0 );   // ensure memory allocated
46     strcpy( firstName, first );
47  
48     lastName = new char[ strlen( last ) + 1 ];
49     assert( lastName != 0 );    // ensure memory allocated
50     strcpy( lastName, last );
51  
52     ++count;  // increment static count of employees
53     cout << "Employee constructor for " << firstName
54          << ' ' << lastName << " called." << endl;
55  }
56  
57  // Destructor deallocates dynamically allocated memory
58  Employee::~Employee()
59  {
60     cout << "~Employee() called for " << firstName
61          << ' ' << lastName << endl;
62     delete firstName;  // recapture memory
63     delete lastName;   // recapture memory
64     --count;  // decrement static count of employees
65  }
66  
67  // Return first name of employee
68  const char *Employee::getFirstName() const
69  {
70     // const before return type prevents client modifying
71     // private data. Client should copy returned string before
72     // destructor deletes storage to prevent undefined pointer.
73     return firstName;
74  }
75  
76  // Return last name of employee
77  const char *Employee::getLastName() const
78  {
79     // const before return type prevents client modifying
80     // private data. Client should copy returned string before
81     // destructor deletes storage to prevent undefined pointer.
82     return lastName;
83  }
84  // Fig. 7.9: fig07_09.cpp
85  // Driver to test the Employee class
86  #include <iostream.h>
87  #include "employ1.h"
88  
89  int main()
90  {
91     cout << "Number of employees before instantiation is "
92          << Employee::getCount() << endl;   // use class name
93  
94     Employee *e1Ptr = new Employee( "Susan", "Baker" );
95     Employee *e2Ptr = new Employee( "Robert", "Jones" );
96  
97     cout << "Number of employees after instantiation is "
98          << e1Ptr->getCount();
99  
100    cout << "\n\nEmployee 1: "
101         << e1Ptr->getFirstName()
102         << " " << e1Ptr->getLastName()
103         << "\nEmployee 2: "
104         << e2Ptr->getFirstName()
105         << " " << e2Ptr->getLastName() << "\n\n";
106 
107    delete e1Ptr;   // recapture memory
108    e1Ptr = 0;
109    delete e2Ptr;   // recapture memory
110    e2Ptr = 0;
111 
112    cout << "Number of employees after deletion is "
113         << Employee::getCount() << endl;
114 
115    return 0;
116 }