This is the assignment.
Change the Game Lobby program from Chapter 9 (pgs 315-325):
Improve the Lobby class by writing a friend function of the Player class that allows a Player object to be sent to std::cout.
Next update the function that allows a Lobby object to be sent to std::cout so that it uses your new function for sending a Player object to std::cout.
The Lobby::AddPlayer() member function is inefficient because it iterates through all of the player nodes to find the end to add the new player. Add an m_ptail pointer data member to the Lobby class that always points to the last player node in the line and use it to more efficiently add a player.
Here is the original code:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
//Game Lobby
//Simulates a game lobby where players wait
#include <iostream>
#include <string>
using namespace std;
class Player
{
public:
Player(const string& name = "");
string GetName() const;
Player* GetNext() const;
void SetNext(Player* next);
private:
string m_Name;
Player* m_pNext; //Pointer to next player in list
};
Player::Player(const string& name):
m_Name(name),
m_pNext(0)
{}
string Player::GetName() const
{
return m_Name;
}
Player* Player::GetNext() const
{
return m_pNext;
}
void Player::SetNext(Player* next)
{
m_pNext = next;
}
class Lobby
{
friend ostream& operator<<(ostream& os, const Lobby& aLobby);
public:
Lobby();
~Lobby();
void AddPlayer();
void RemovePlayer();
void Clear();
private:
Player* m_pHead;
};
Lobby::Lobby():
m_pHead(0)
{}
Lobby::~Lobby()
{
Clear();
}
void Lobby::AddPlayer()
{
//create a new player node
cout << "Please enter the name of the new player: ";
string name;
cin >> name;
Player* pNewPlayer = new Player(name);
//if list is empty, make head of list this new player
if (m_pHead == 0)
{
m_pHead = pNewPlayer;
}
//otherwise find the end of the list and add the player there
else
{
Player* pIter = m_pHead;
while (pIter->GetNext() != 0)
{
pIter = pIter->GetNext();
}
pIter->SetNext(pNewPlayer);
}
}
void Lobby::RemovePlayer()
{
if (m_pHead == 0)
{
cout << "The game lobby is empty. No one to remove!\n";
}
else
{
Player* pTemp = m_pHead;
m_pHead = m_pHead->GetNext();
delete pTemp;
}
}
void Lobby::Clear()
{
while (m_pHead != 0)
{
RemovePlayer();
}
}
ostream& operator<<(ostream& os, const Lobby& aLobby)
{
Player* pIter = aLobby.m_pHead;
os << "\nHere's who's in the game lobby:\n";
if (pIter == 0)
{
os << "The lobby is empty.\n";
}
else
{
while (pIter != 0)
{
os << pIter->GetName() << endl;
pIter = pIter->GetNext();
}
}
return os;
}
int main()
{
Lobby myLobby;
int choice;
do
{
cout << myLobby;
cout << "\nGAME LOBBY\n";
cout << "0 - Exit the program.\n";
cout << "1 - Add a player to the lobby.\n";
cout << "2 - Remove a player from the lobby.\n";
cout << "3 - Clear the lobby.\n";
cout << endl << "Enter choice: ";
cin >> choice;
switch (choice)
{
case 0: cout << "Good-bye.\n"; break;
case 1: myLobby.AddPlayer(); break;
case 2: myLobby.RemovePlayer(); break;
case 3: myLobby.Clear(); break;
default: cout << "That was not a valid choice.\n";
}
}
while (choice != 0);
return 0;
}
|
Here is my code:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
//Game Lobby
//Simulates a game lobby where players wait
#include <iostream>
#include <string>
using namespace std;
class Player
{
friend ostream& operator<<(ostream& os, const Player& aPlayer); //friend function of player class
public:
Player(const string& name = "");
string GetName() const;
Player* GetNext() const;
void SetNext(Player* next);
private:
string m_Name;
Player* m_pNext; //Pointer to next player in list
};
Player::Player(const string& name) :
m_Name(name),
m_pNext(0)
{}
string Player::GetName() const
{
return m_Name;
}
Player* Player::GetNext() const
{
return m_pNext;
}
void Player::SetNext(Player* next)
{
m_pNext = next;
}
class Lobby
{
friend ostream& operator<<(ostream& os, const Lobby& aLobby);
public:
Lobby();
~Lobby();
void AddPlayer();
void RemovePlayer();
void Clear();
private:
Player* m_pHead;
Player* m_pTail; // add pointer to lobby for last player node
};
Lobby::Lobby() :
m_pHead(0),
m_pTail(0) //set last player node to 0
{}
Lobby::~Lobby()
{
Clear();
}
void Lobby::AddPlayer()
{
//create a new player node
cout << "Please enter the name of the new player: ";
string name;
cin >> name;
Player* pNewPlayer = new Player(name);
//if list is empty, make head of list this new player
if (m_pHead == 0)
{
m_pHead = pNewPlayer;
}
//otherwise find the end of the list and add the player there
else
{
Player* pIter = m_pHead;
while (pIter->GetNext() != 0)
{
pIter = pIter->GetNext();
}
pIter->SetNext(pNewPlayer);
pIter = pIter->GetNext();
m_pTail = pIter; //assign last node to iterator
}
}
void Lobby::RemovePlayer()
{
if (m_pHead == 0)
{
cout << "The game lobby is empty. No one to remove!\n";
}
else
{
Player* pTemp = m_pHead;
m_pHead = m_pHead->GetNext();
delete pTemp;
}
}
void Lobby::Clear()
{
while (m_pHead != 0)
{
RemovePlayer();
}
}
ostream& operator<<(ostream& os, const Lobby& aLobby)
{
Player* pIter = aLobby.m_pHead;
os << "\nHere's who's in the game lobby:\n";
if (pIter == 0)
{
os << "The lobby is empty.\n";
}
else
{
while (pIter != 0)
{
os << *pIter<< endl; // dereference iterator
pIter = pIter->GetNext();
}
}
return os;
}
int main()
{
Lobby myLobby;
int choice;
do
{
cout << myLobby;
cout << "\nGAME LOBBY\n";
cout << "0 - Exit the program.\n";
cout << "1 - Add a player to the lobby.\n";
cout << "2 - Remove a player from the lobby.\n";
cout << "3 - Clear the lobby.\n";
cout << endl << "Enter choice: ";
cin >> choice;
switch (choice)
{
case 0: cout << "Good-bye.\n"; break;
case 1: myLobby.AddPlayer(); break;
case 2: myLobby.RemovePlayer(); break;
case 3: myLobby.Clear(); break;
default: cout << "That was not a valid choice.\n";
}
} while (choice != 0);
return 0;
}
|
I get the following two errors when i try to debug:
Error LNK2019 unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Player const &)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@ABVPlayer@@@Z) referenced in function "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Lobby const &)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@ABVLobby@@@Z) GameLobby1 F:\C++\GameLobby1\GameLobby1\GameLobbyFriend.obj 1
Error LNK1120 1 unresolved externals GameLobby1 F:\C++\GameLobby1\Debug\GameLobby1.exe 1
I guess my question is what did i do wrong and also did i cover all the bases on the assignment? Thanks in advance.
