Sequence Class

[mathon]

Hallo,

Ich muss eine Sequence Klasse bauen, das header-file dafür ist vorgegeben:

class sequence
    {
    public:
        // TYPEDEFS and MEMBER CONSTANTS
        typedef double value_type;
        typedef std::size_t size_type;
        static const size_type DEFAULT_CAPACITY = 30;
        // CONSTRUCTORS and DESTRUCTOR
        sequence(size_type initial_capacity = DEFAULT_CAPACITY);
        sequence(const sequence& source);
		~sequence( );
        // MODIFICATION MEMBER FUNCTIONS
		void resize(size_type new_capacity);
        void start( );
        void advance( ); //set the current_index to the next number in the array
        void insert(const value_type& entry); //insert before the number with the current index
        void attach(const value_type& entry); //insert after the number with the current index
        void remove_current( );
        void operator =(const sequence& source);
        // CONSTANT MEMBER FUNCTIONS
        size_type size( ) const;
        bool is_item( ) const;
        value_type current( ) const;
    private:
        value_type* data; //das array mit den zahlen drinnen
        size_type used; //wieviele zahlen in dem array stehen
        size_type current_index;
	size_type capacity;
    };

Leider stimmt bei mir beim copy-constructor anscheinend irgendwas nicht, aber ich komme einfach nicht drauf was hier falsch ist:

sequence::sequence(const sequence& source)
{
	data = new value_type[source.capacity];
	capacity = source.capacity;
	used = source.used;
	current_index = source.current_index;
	copy(source.data, source.data + used, data);
}

Hier auch noch die insert, attach und resize funktionen:

void sequence::insert(const value_type& entry)
{
	if(used == capacity)
		resize(used);

	if(!(is_item()))
		current_index = 0;

	for(int i = used; i > current_index; i--)
	{
		data[i] = data[i-1];
	}
	data[current_index] = entry;
	++used;
}

void sequence::attach(const value_type& entry)
{
	if(used == capacity)
		resize(used);

	if(current_index >= used)
	{
		start();
		advance();
		advance();
	}
	if(used!=0)
	{
		for(int i = used; i > current_index+1; i--)
		{
			data[i] = data[i-1];
		}
		data[current_index+1] = entry;
		current_index++;
	}
	else
	{
		data[current_index] = entry;
	}
	++used;
}

void sequence::resize (size_type new_capacity)
{
	value_type* larger_array;

	if(new_capacity < used)
		new_capacity = used;

	larger_array = new value_type[new_capacity];
	copy(data, data + used + current_index, larger_array);
	delete[] data;
	data = larger_array;
	capacity = new_capacity;
}

Hat irgendjemand von euch ne Ahnung was hier falsch läuft? - Ich arbeite daran jetzt schon solange daran und bin schon kurz vorm verzweifeln...

lg matti

 

[mathon]

Hier ist das test-programm, das ich verwende:

int test5( )
{
    sequence original; // A sequence that we'll copy.
    double items[2*original.DEFAULT_CAPACITY];
    size_t i;

    // Set up the items array to conatin 1...2*DEFAULT_CAPACITY.
    for (i = 1; i <= 2*original.DEFAULT_CAPACITY; i++)
        items[i-1] = i;
    
    // Test copying of an empty sequence. After the copying, we change the original.
    cout << "Copy constructor test: for an empty sequence." << endl;
    sequence copy1(original);
    original.attach(1); // Changes the original sequence, but not the copy.
    if (!correct(copy1, 0, 0, items)) return 0;

    // Test copying of a sequence with current item at the tail.
    cout << "Copy constructor test: for a sequence with cursor at tail." << endl;
    for (i=2; i <= 2*original.DEFAULT_CAPACITY; i++)
        original.attach(i);
	cout << "SIZE: " << original.size() << endl;
    sequence copy2(original);
    original.start( );
    original.advance( );
    original.remove_current( ); // Removes 2 from the original, but not the copy.
    if (!correct
        (copy2, 2*original.DEFAULT_CAPACITY, 2*original.DEFAULT_CAPACITY-1, items)
        )
        return 0;

    // Test copying of a sequence with cursor near the middle.
    cout << "Copy constructor test: for a sequence with cursor near middle." << endl;
    original.insert(2);
    for (i = 1; i < original.DEFAULT_CAPACITY; i++)
        original.advance( );
    // Cursor is now at location [DEFAULT_CAPACITY] (counting [0] as the first spot).
    sequence copy3(original);
    original.start( );
    original.advance( );
    original.remove_current( ); // Removes 2 from the original, but not the copy.
    if (!correct
        (copy3, 2*original.DEFAULT_CAPACITY, original.DEFAULT_CAPACITY, items)
        )
        return 0;

    // Test copying of a sequence with cursor at the front.
    cout << "Copy constructor test: for a sequence with cursor near middle." << endl;
    original.insert(2);
    original.start( );
    // Cursor is now at the front.
    sequence copy4(original);
    original.start( );
    original.advance( );
    original.remove_current( ); // Removes 2 from the original, but not the copy.
    if (!correct
        (copy4, 2*original.DEFAULT_CAPACITY, 0, items)
        )
        return 0;

    // Test copying of a sequence with no current item.
    cout << "Copy constructor test: for a sequence with no current item." << endl;
    original.insert(2);
    while (original.is_item( ))
        original.advance( );
    // There is now no current item.
    sequence copy5(original);
    original.start( );
    original.advance( );
    original.remove_current( ); // Removes 2 from the original, but not the copy.
    if (!correct
        (copy5, 2*original.DEFAULT_CAPACITY, 2*original.DEFAULT_CAPACITY, items)
        )
        return 0;
}

Nach der Zeile cout << "Copy constructor test: for a sequence with cursor near middle." << endl; bricht das Programm ab und es erscheint ein Popup-Fenster, wo steht, dass das Programm einen Fehler festgestellt hat und beendet werden musste.

Ich glaube der Fehler passiert eigentlich bei dem insert statement danach.

Hat jemand von euch ne ahnung..?

matti

 

[Endurion]

Ohne gross draufzublicken kommt mir der copy-Aufruf in deinem Copy-Constructor komisch für:

copy( source.data, source.data + used, data );

Müsstest du nicht das komplette data kopieren, du kopierst ja auch den used-Zeiger?

 

[mathon]

Ich habe den fehler bereits gefunden, ich habe used nicht vergrößert als ich es der resize funktion übergeben habe, jetzt habe ich 2*used soowohl bei insert und attach und jetzt funktionierts!

Danke trotzdem für die Hilfe!