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Alloc dealloc

Started by Leadorn Jan 31, 2003 at 6:16 AM 6 replies 250+ views

Original Post

Jan 31, 2003 at 6:16 AM

Ive tried this q in the beginner pool but cant get an answer. If I use this code for my 2d array, is this the correct way to deallocate the array?

  
alloc
int **Map;
Map = new int*[ARRAY_WIDTH];
for (int i = 0; i < ARRAY_WIDTH; i++)
    Map[ i ] = new int[ARRAY_HEIGHT];

dealloc
for (unsigned int i = 0; i < ARRAY_WIDTH; i++)	
{			
delete [] Map[i];
}
delete [] Map;

prgrmmr

Jan 31, 2003 at 6:46 AM

I dont''t like ''new'', but this is correct.

    
//alloc

int **Map;
Map = (INT**)malloc( ARRAY_WIDTH*sizeof(INT*) );
for (int i = 0; i < ARRAY_WIDTH; i++)
  Map[i] = (INT*)malloc( ARRAY_WIDTH*sizeof(INT) );

//dealloc

for (unsigned int i = 0; i < ARRAY_WIDTH; i++)	
{			
free( Map[i] );
}
free( Map );

prgrmmr

Jan 31, 2003 at 6:46 AM

I dont''t like ''new'', but this is correct.

    
//alloc

int **Map;
Map = (INT**)malloc( ARRAY_WIDTH*sizeof(INT*) );
for (int i = 0; i < ARRAY_WIDTH; i++)
  Map[i] = (INT*)malloc( ARRAY_WIDTH*sizeof(INT) );

//dealloc

for (unsigned int i = 0; i < ARRAY_WIDTH; i++)	
{			
free( Map[i] );
}
free( Map );

Kippesoep

Jan 31, 2003 at 6:51 AM

If you don't want to bother with the for-loops, but still want a 2D array, try this:

MATRIX.H

  
template <class T, int columns>
class MATRIX
{
public :
	MATRIX (T *data)
	{
		_data = data;
	}

	T *operator [] (int row)
	{
		return _data + (row * columns);
	}

protected :
	T *_data;
};

and in your code, include MATRIX.H and do something like

  
int *Map1D = new int [ARRAY_WIDTH * ARRAY_HEIGHT];
MATRIX <int, ARRAY_HEIGHT> Map (Map1D);

//Here, you can use Map just as your array of arrays:

Map [10][15] = 1;

//Then, just free it like this:

delete [] Map1D;

[edited by - Kippesoep on January 31, 2003 7:53:33 AM]

Leadorn

Author

Leadorn

Jan 31, 2003 at 12:27 PM

And this reminds my about another problem I have. I've created a class cNode. I’ve done it with templates so I can store any kind of type. It all works good, but when I want to use it in my big project I get link problems.

error LNK2001: unresolved external symbol "public: __thiscall cNode::~cNode(void)" (??1?$cNode@H@@QAE@XZ)

unresolved external symbol "public: __thiscall cNode::cNode(void)" (??0?$cNode@H@@QAE@XZ)

I've tried it out and it works in my test project with only it in it.

This is my first time making a template, any suggestions for changes are appreciated.

    
I use it like this, cNode<int> View;

///Header

template <class Type>
class cNode
{
public:
	struct sNode
	{
		Type *item;
		sNode *Next;
	};
	
	cNode();
	~cNode();
	bool Add(Type *item);
	bool GetItem(Type **item);
	void ResetCount();
	
	private:
		//Front of linked list.

		sNode *Front;
		sNode *End;
		
		sNode *NodePitch;
		bool bLocked;					
};

//cpp

template <class Type>
cNode<Type>::cNode()
{
	End = Front = 0;
	bLocked = false;
}


template <class Type>
cNode<Type>::~cNode()
{
	sNode		*Pitch;
	sNode		*TempPitch;
	
	Pitch = Front;

	while(Pitch != 0)
	{
			
		TempPitch = Pitch;
		Pitch = Pitch->Next;
	
		delete TempPitch->item;
		delete TempPitch;		
	}//End of while(ChannelPitch != 0)

	
}




template <class Type>
bool cNode<Type>::Add(Type *item)
{
	if(bLocked == true) return false;
	if (item == 0) return false;
	
	if(Front == 0)
	{
		Front = new sNode;
		if(Front == 0) return false;		
		Front->Next = 0;
		End = Front;		
		//Set input.

		End->item = item;
		NodePitch = Front;
		
		return true;
	}
	else
	{
		End->Next = new sNode;
		if(End->Next == 0) return false;
		End->Next->Next = 0;
		End = End->Next;
		//Set input.

		End->item = item;
		return true;
	}
	return false;
}

template <class Type>
bool cNode<Type>::GetItem(Type **item)
{
	//Lock class.

	bLocked = true;
	
	if(NodePitch == 0) return false;
	
	
	*item = NodePitch->item;
	
	
	NodePitch = NodePitch->Next;
	return true;
}

template <class Type>
void cNode<Type>::ResetCount()
{
	
	NodePitch = Front;
	
	
}