C++

Forum

 
Templates and abstract classes

yoked88 (140)
Hey guys, I'm getting an error from the compiler telling me that I have an abstract class but all the virtual functions are defined in it, not sure what is going on. Can someone help?

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
 
#ifndef H_arrayListType
#define H_arrayListType

#include <iostream>

using namespace std;

template <class elemType>
class arrayListType
{
public:
	const arrayListType<elemType>& operator=(const arrayListType<elemType>&);//
	bool isEmpty() const;//
	bool isFull() const;//
	int listSize() const;//
	int maxListSize() const;//
	void print() const;//
	bool isItemAtEqual(int,const elemType&) const;//
	virtual void insertAt(int location,const elemType& insertItem) = 0;//
	virtual void insertEnd(const elemType& insertItem) = 0;//
	void removeAt(int);//
	void retrieveAt(int,elemType&) const;//
	virtual void replaceAt(int location, const elemType& repItem) = 0;//
	void clearList();//
	virtual int seqSearch(const elemType& searchItem) = 0;//
	virtual void remove(const elemType& removeItem) = 0;//
	arrayListType(int size = 100);//
	arrayListType(const arrayListType<elemType>& otherList);//
	virtual ~arrayListType();//
protected:
	elemType *list;
	int length;
	int maxSize;
};

template <class elemType>
void arrayListType<elemType>::print() const
{
	for(int i = 0; i < length; i++)
		cout << list[i] << " ";
	cout << endl;
}

template <class elemType>
bool arrayListType<elemType>::isItemAtEqual(int location, const elemType& item) const
{
	if(location < 0 || location >= length)
	{
		cout << "Location is out of range. " << endl;
		return false;
	}
	else
		return (list[location] == item);
}

template <class elemType>
void arrayListType<elemType>::removeAt(int location)
{
	if(location < 0 || location >= length)
		cout << "Location is out of range." << endl;
	else
	{
		for(int i = location; i < length; i++)
			list[i] = list[i + 1];
		length--;
	}
}

template <class elemType>
void arrayListType<elemType>::retrieveAt(int location, elemType& retItem) const
{
	if(location < 0 || location >= length)
		cout << "Location is oit of range." << endl;
	else
		retItem = list[location];
}

template <class elemType>
arrayListType<elemType>::arrayListType(int size)
{
	if(size <= 0)
	{
		cout << "Size must be positive, creating default size of 100." << endl;
		maxSize = 100;
	}
	else
		maxSize = size;
	length = 0;
	list = new elemType[maxSize];
}

template <class elemType>
arrayListType<elemType>::~arrayListType()
{
	delete [] list;
}

template <class elemType>
const arrayListType<elemType>& arrayListType<elemType>::operator =(const arrayListType<elemType>& otherList)
{
	if(this != &otherList)
	{
		delete [] list;
		maxSize = otherList.maxSize;
		length = otherList.length;
		list = new elemType[maxSize];
		for(int i = 0; i < length; i++)
			list[i] = otherList.list[i];
	}
	return *this;
}

template <class elemType>
bool arrayListType<elemType>::isEmpty() const
{
	return (length == 0);
}

template <class elemType>
bool arrayListType<elemType>::isFull() const
{
	return (length == maxSize);
}

template <class elemType>
int arrayListType<elemType>::listSize() const
{
	return length;
}

template <class elemType>
int arrayListType<elemType>::maxListSize() const
{
	return maxSize;
}

template <class elemType>
void arrayListType<elemType>::clearList()
{
	length = 0;
}

template <class elemType>
arrayListType<elemType>::arrayListType(const arrayListType<elemType> &otherList)
{
	maxSize = otherList.maxSize;
	length = otherList.length;
	list = new elemType[maxSize];
	for(int i = 0; i < length; i++)
		list[i] = otherList.list[i];
}

#endif 



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
 
#ifndef H_unorderedArrayListType
#define H_unorderedArrayListType
#include "arrayListType.h"
#include <iostream>

using namespace std;

template <class elemType>
class unorderedArrayListType: public arrayListType<elemType>
{
public:
	void insertAt(int location,const elemType& insertItem);//
	void insertEnd(const elemType& insertItem);//
	void replaceAt(int location,const elemType& repItem);//
	int seqSearch(const elemType& searchItem) const;//
	void remove(const elemType& removeItem);//
	unorderedArrayListType(int size = 100);//
};

template <class elemType>
void unorderedArrayListType<elemType>::insertEnd(const elemType& insertItem)
{
	if(length >= maxSize)
		cout << "The list is full. " << endl;
	else
	{
		list[length] = insertItem;
		length++;
	}
}

template <class elemType>
int unorderedArrayListType<elemType>::seqSearch(const elemType& searchItem) const
{
	int loc;
	bool found = false;
	for(loc = 0; loc < length; loc++)
		if(list[loc] == searchItem)
		{
			found = true;
			break;
		}
	if(found)
		return loc;
	else
		return -1;
}

template <class elemType>
void unorderedArrayListType<elemType>::remove(const elemType& removeItem)
{
	int loc;
	if(length == 0)
		cout << "The list is empty. " << endl;
	else
	{
		loc = seqSearch(removeItem);
		if(loc != -1)
			removeAt(loc);
		else
			cout << "The item is not in the list. " << endl;
	}
}

template <class elemType>
void unorderedArrayListType<elemType>::replaceAt(int location, const elemType& repItem)
{
	if(location < 0 || location >= length)
		cout << "Location is out of range. " << endl;
	else
		list[location] = repItem;
}

template <class elemType>
void unorderedArrayListType<elemType>::insertAt(int location, const elemType& insertItem)
{
	if(location < 0 || location >= maxSize)
		cout << "Location is out of range." << endl;
	else if (length >= maxSize)
		cout << "The list is full. " << endl;
	else
	{
		for(int i = length; i > location; i--)
			list[i] = list[i - 1];
		list[location] = insertItem;
		length++;
	}
}

template <class elemType>
unorderedArrayListType<elemType>::unorderedArrayListType(int size)
                                   :arrayListType<elemType>(size)
{
}

#endif 



1
2
3
4
5
6
7
8
9
10
11
12
13
 
#include <iostream>
#include <string>
#include "unorderedArrayListType.h"

using namespace std;

int main()
{
	unorderedArrayListType<string> strList(25);
	unorderedArrayListType<int> intList(25);
	system("PAUSE");
	return 0;
}




1>c:\users\joseph\documents\visual studio 2008\projects\moreexamples\moreexamples\main.cpp(10) : error C2259: 'unorderedArrayListType<elemType>' : cannot instantiate abstract class
1>        with
1>        [
1>            elemType=std::string
1>        ]
1>        due to following members:
1>        'int arrayListType<elemType>::seqSearch(const elemType &)' : is abstract
1>        with
1>        [
1>            elemType=std::string
1>        ]
1>        c:\users\joseph\documents\visual studio 2008\projects\moreexamples\moreexamples\arraylisttype.h(25) : see declaration of 'arrayListType<elemType>::seqSearch'
1>        with
1>        [
1>            elemType=std::string
1>        ]
1>c:\users\joseph\documents\visual studio 2008\projects\moreexamples\moreexamples\main.cpp(11) : error C2259: 'unorderedArrayListType<elemType>' : cannot instantiate abstract class
1>        with
1>        [
1>            elemType=int
1>        ]
1>        due to following members:
1>        'int arrayListType<elemType>::seqSearch(const elemType &)' : is abstract
1>        with
1>        [
1>            elemType=int
1>        ]
1>        c:\users\joseph\documents\visual studio 2008\projects\moreexamples\moreexamples\arraylisttype.h(25) : see declaration of 'arrayListType<elemType>::seqSearch'
1>        with
1>        [
1>            elemType=int
1>        ]
1>Build log was saved at "file://c:\Users\Joseph\Documents\Visual Studio 2008\Projects\MoreExamples\MoreExamples\Debug\BuildLog.htm"
TheIdeasMan (6817)
You need to redefine ALL the pure virtual functions in the derived class, otherwise the class is incomplete - that is still abstract, because the all the functions are inherited.

HTH
yoked88 (140)
The pure virtual functions are omitted from the base class and defined in the derived class. Would you mind giving me an example of what I need to do?
Topic archived. No new replies allowed.