Linked List Queue Implementation help

This is a discussion on Linked List Queue Implementation help within the C++ Programming forums, part of the General Programming Boards category; I have been studying C++ for a year now, and I've started a small test project: A linked list container ...

  1. #1
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    Linked List Queue Implementation help

    I have been studying C++ for a year now, and I've started a small test project: A linked list container library. I'm using Dev-C++, and when I try to compile the listing, it gives me the errors:
    Compiler: Default compiler
    Executing g++.exe...
    g++.exe "C:\Documents and Settings\Stephen\Desktop\Nathan\Programming Languages\C++\Kenogu's Container Library\QueueTest.cpp" -o "C:\Documents and Settings\Stephen\Desktop\Nathan\Programming Languages\C++\Kenogu's Container Library\QueueTest.exe" -fexceptions -pg -g3 -I"C:\Program Files\Dev C++\Dev-Cpp\include\c++" -I"C:\Program Files\Dev C++\Dev-Cpp\include\c++\backward" -I"C:\Program Files\Dev C++\Dev-Cpp\include" -I"C:\Program Files\Dev C++\Dev-Cpp\include\c++\mingw32" -I"C:\Program Files\Dev C++\Dev-Cpp\include\c++\random" -L"C:\Program Files\Dev C++\Dev-Cpp\lib" -L"C:\Program Files\Dev C++\Dev-Cpp\Allegro\Lib"
    In file included from C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:12,
    from C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:2:
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.hpp:26: `

    LLQueue' is not a template type
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.hpp:34: data
    member `head' cannot be a member template
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.hpp:35: data
    member `tail' cannot be a member template
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.hpp:36: data
    member `size' cannot be a member template
    In file included from C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:2:
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:19: non-template
    type `LLQueue' used as a template
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:20: ISO
    C++ forbids declaration of `LLQueue' with no type
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp: In
    function `int LLQueue()':
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:20: only
    constructors take base initializers
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp: At
    global scope:
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:23: syntax
    error before `::' token
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:23: `
    t' was not declared in this scope
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:23: `
    InData' was not declared in this scope
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:23: ISO
    C++ forbids declaration of `push' with no type

    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:23: syntax
    error before `{' token
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:27: ISO

    C++ forbids declaration of `tail' with no type
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:27: `
    node' was not declared in this scope
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:28: parse
    error before `if'
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:30: syntax

    error before `++' token
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:34: syntax
    error before `::' token
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:34: ISO
    C++ forbids declaration of `pop' with no type
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp: In
    function `int pop()':
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:35: `
    size' undeclared (first use this function)
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:35: (Each
    undeclared identifier is reported only once for each function it appears
    in.)

    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:37: `
    t' undeclared (first use this function)
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:37: parse
    error before `=' token
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:38: `

    LLQueueNode' undeclared (first use this function)
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:39: `
    head' undeclared (first use this function)
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:40: `
    newHead' undeclared (first use this function)
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/Queue.cpp:42: `
    data' undeclared (first use this function)
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp: In
    function `int main()':
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:6: parse
    error before `(' token
    C:/Documents and Settings/Stephen/Desktop/Nathan/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:11: `
    q' undeclared (first use this function)

    Execution terminated
    Here is the code used:
    Code:
    /*
    		 			-=Linked List queue=-
    				 -=COPYRIGHT KENOGU LABZ 2005=-
    
    Classes used:
    LLQueue
    LLQueueNode
    */
    #ifndef QUEUE_HPP
    #define QUEUE_HPP
    
    class LLQueue;
    
    template <class t>
    class LLQueueNode {
    public:
    	LLQueueNode(t * InData, LLQueueNode * InNext);
    	~LLQueueNode(){delete data; delete next;}
    	friend class LLQueue;
    private:
    	t * data;
    	LLQueueNode<t> * next;
    };
    
    template <class t>
    class LLQueue {
    public:
    	LLQueue();
    	~LLQueue(){delete head; delete tail;}
    	void push(t * InData);
    	t * pop();
    	int getSize() {return size;}
    private:
    	LLQueueNode<t> * head;
    	LLQueueNode<t> * tail;
    	int size;
    };
    
    class Empty{};
    
    #endif
    -------------------------------------------------------------------
    
    /*
    		 			-=Linked List queue=-
    				 -=COPYRIGHT KENOGU LABZ 2005=-
    
    Classes used:
    Queue
    QueueNode
    */
    #ifndef QUEUE_CPP
    #define QUEUE_CPP
    
    #include "Queue.hpp"
    
    template <class t>
    LLQueueNode<t>::LLQueueNode(t * InData, LLQueueNode * InNext)
    	:data(InData), next(InNext){}
    
    template <class t>
    LLQueue<t>::LLQueue()
    	:head(0), tail(0), size(0){}
    
    template <class t>
    LLQueue<t>::push(t * InData) {
    	LLQueueNode* node = new LLQueueNode(InData, 0);
    	if(size)
    		tail->next = node;
    	tail = node;
    	if(!size)
    		head = node;
    	size++;
    }
    
    template <class t>
    t LLQueue<t>::pop() {
    	if(!size)
    		throw Empty();
    	t data = head->data;
    	LLQueueNode newHead = head->next;
    	delete head;
    	head = newHead;
    	size--;
    	return data;
    }
    -----------------------------------------------------------------
    
    #include <iostream>
    #include "Queue.cpp"
    using namespace std;
    
    int main() {
    	LLQueue<int> q();
    	unsigned short choice;
    	 do {
    		 cout << "Enter a number to add to the queue (0 to exit): ";
    		 cin >> choice;
    		 q.push(new int(choice));
    	 } while(choice!=0);
    	 try {
    		 cout << "Queue Size: " << q.getSize() << endl;
    		 cout << "Next value: " << q.pop() << endl;
    	}
    	catch(Empty) {}
    	cout << "End of Queue. (Press CTRL-Z)";
    	char leave;
    	do
    		cin >> leave;
    	while(leave != EOF);
    	return 0;
    }
    Could anyone tell me why this isn't compiling? Design criticisms are welcome, too.

    -=Kenogu Labz=-

  2. #2
    Cheesy Poofs! PJYelton's Avatar
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    The vast majority of your errors are because you declare LLQueue as a simple class by saying:
    Code:
    class LLQueue;
    but then later on when you implement it you say its a template class. Change the line to:
    Code:
    template <class t> class LLQueue;
    Also, you can't have a line of dashes without commenting them out.

    [edit]nevermind, i'm guessing you just added the lines to distinguish between files[/edit]
    Last edited by PJYelton; 09-20-2005 at 02:24 PM.

  3. #3
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    Wow, that really helped. Didn't know that prototypes had to be declared as templates, too (although it makes perfect sense.) Now there's only 19 errors left. :P
    The only other thing that's bugging me is the constant "ISO forbids declaration of 'push' with no type" message. Is that saying it is neccessary to have a return type?

  4. #4
    Cheesy Poofs! PJYelton's Avatar
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    You have several errors because you are using the template without declaring the type, for example:
    Code:
    LLQueueNode* node = new LLQueueNode(InData, 0);
    should be
    Code:
    LLQueueNode<t>* node = new LLQueueNode<t>(InData, 0);
    Also, you are routinely are declaring variables as pointers and then later on using them as non-pointers, such as trying to print a pointer to an integer.

    The error you are talking about with push() is because you forgot to put "void" when defining it.

  5. #5
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    Lol, I'm too sloppy for my own good. Thanks alot for your help, again!
    And I'm pretty sure this is the last problem; I fixed all but 3 errors; they say:
    C:/Documents and Settings/*****/Desktop/*****/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:11: request
    for member `push' in `q()', which is of non-aggregate type `LLQueue<int>
    ()()'
    C:/Documents and Settings/*****/Desktop/*****/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:14: request
    for member `getSize' in `q()', which is of non-aggregate type `LLQueue<int>
    ()()'
    C:/Documents and Settings/*****/Desktop/*****/Programming Languages/C++/Kenogu's Container Library/QueueTest.cpp:15: request
    for member `pop' in `q()', which is of non-aggregate type `LLQueue<int> ()()
    Okay, could you tell me what that error is supposed to mean? I'll try to remember all these for future reference; at the moment, it's all mumbo jumbo, though.
    Last edited by Kenogu Labz; 09-21-2005 at 01:40 PM.

  6. #6
    Cheesy Poofs! PJYelton's Avatar
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    Get rid of the () in this line and see if it helps:
    Code:
    LLQueue<int> q();

  7. #7
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    WOAH, that didn't work at all. Gave me 25 more errors. What is the error message implying?

  8. #8
    Cheesy Poofs! PJYelton's Avatar
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    Post the new code, I've never seen the error before but I'm pretty sure its because you have the unnecessary parenthesis when declaring q.

  9. #9
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    PROBLEM SOLVED! Thanks for all your help, PJYelton. ;)
    Last edited by Kenogu Labz; 09-21-2005 at 01:55 PM.

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