Qt 4.3: Q3PtrVector Class Reference

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# Q3PtrVector Class Reference
[Qt3Support module]

The Q3PtrVector class is a template collection class that provides a vector (array). More...

     #include <Q3PtrVector>

This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.

Inherits Q3PtrCollection.

- List of all members, including inherited members

### Public Functions

- Q3PtrVector ()
- Q3PtrVector ( uint size )
- Q3PtrVector ( const Q3PtrVector<type> & v )
- ~Q3PtrVector ()
- type * at ( uint i ) const
- int bsearch ( const type * d ) const
- virtual void clear ()
- uint contains ( const type * d ) const
- uint containsRef ( const type * d ) const
- virtual uint count () const
- type ** data () const
- bool fill ( const type * d, int size = -1 )
- int find ( const type * d, uint i = 0 ) const
- int findRef ( const type * d, uint i = 0 ) const
- bool insert ( uint i, const type * d )
- bool isEmpty () const
- bool isNull () const
- bool remove ( uint i )
- bool resize ( uint size )
- uint size () const
- void sort ()
- type * take ( uint i )
- Q3PtrVector<type> & operator= ( const Q3PtrVector<type> & v )
- bool operator== ( const Q3PtrVector<type> & v ) const
- type * operator[] ( int i ) const

- 4 public functions inherited from Q3PtrCollection

### Protected Functions

- virtual int compareItems ( Q3PtrCollection::Item d1, Q3PtrCollection::Item d2 )
- virtual QDataStream & read ( QDataStream & s, Q3PtrCollection::Item & item )
- virtual QDataStream & write ( QDataStream & s, Q3PtrCollection::Item item ) const

- 2 protected functions inherited from Q3PtrCollection

## Detailed Description

The Q3PtrVector class is a template collection class that provides a vector (array).

Q3ValueVector is an STL-compatible alternative to this class.

Q3PtrVector is implemented as a template class. Defines a template instance Q3PtrVector<X> to create a vector that contains pointers to X (X*).

A vector is the same as an array. The main difference between Q3PtrVector and Q3MemArray is that Q3PtrVector stores pointers to the elements, whereas Q3MemArray stores the elements themselves (i.e. Q3MemArray is value-based and Q3PtrVector is pointer-based).

Items are added to the vector using insert() or fill(). Items are removed with remove(). You can get a pointer to an item at a particular index position using at().

Unless otherwise stated, all functions that remove items from the vector will also delete the element pointed to if auto-deletion is enabled. By default, auto-deletion is disabled; see setAutoDelete(). This behavior can be changed in a subclass by reimplementing the virtual function deleteItem().

Functions that compare items (find() and sort() for example) will do so using the virtual function compareItems(). The default implementation of this function only compares the pointer values. Reimplement compareItems() in a subclass to get searching and sorting based on the item contents. You can perform a linear search for a pointer in the vector using findRef(), or a binary search (of a sorted vector) using bsearch(). You can count the number of times an item appears in the vector with contains() or containsRef().

See also Q3MemArray.

## Member Function Documentation

### Q3PtrVector::Q3PtrVector ()

Constructs a null vector.

See also isNull().

### Q3PtrVector::Q3PtrVector ( uint size )

Constructs an vector with room for size items. Makes a null vector if size == 0.

All size positions in the vector are initialized to 0.

See also size(), resize(), and isNull().

### Q3PtrVector::Q3PtrVector ( const Q3PtrVector<type> & v )

Constructs a copy of v. Only the pointers are copied (i.e. shallow copy).

### Q3PtrVector::~Q3PtrVector ()

Removes all items from the vector, and destroys the vector itself.

See also clear().

### type * Q3PtrVector::at ( uint i ) const

Returns the item at position i, or 0 if there is no item at that position. i must be less than size().

### int Q3PtrVector::bsearch ( const type * d ) const

In a sorted array, finds the first occurrence of d using a binary search. For a sorted array, this is generally much faster than find(), which performs a linear search.

Returns the position of d, or -1 if d could not be found. d must not be 0.

Compares items using the virtual function compareItems().

See also sort() and find().

### void Q3PtrVector::clear () `[virtual]`

Removes all items from the vector, and destroys the vector itself.

The vector becomes a null vector.

Reimplemented from Q3PtrCollection.

See also isNull().

### int Q3PtrVector::compareItems ( Q3PtrCollection::Item d1, Q3PtrCollection::Item d2 ) `[virtual protected]`

This virtual function compares two list items.

Returns:

- zero if d1 == d2
- nonzero if d1 != d2

This function returns int rather than bool so that reimplementations can return one of three values and use it to sort by:

- 0 if d1 == d2
- > 0 (positive integer) if d1 > d2
- < 0 (negative integer) if d1 < d2

The sort() and bsearch() functions require compareItems() to be implemented as described here.

This function should not modify the vector because some const functions call compareItems().

### uint Q3PtrVector::contains ( const type * d ) const

Returns the number of occurrences of item d in the vector.

Compares items using the virtual function compareItems().

See also containsRef().

### uint Q3PtrVector::containsRef ( const type * d ) const

Returns the number of occurrences of the item pointer d in the vector.

This function does not use compareItems() to compare items.

See also findRef().

### uint Q3PtrVector::count () const `[virtual]`

Returns the number of items in the vector. The vector is empty if count() == 0.

Reimplemented from Q3PtrCollection.

See also isEmpty(), size(), and isNull().

### type ** Q3PtrVector::data () const

Returns a pointer to the actual vector data, which is an array of type*.

The vector is a null vector if data() == 0 (null pointer).

See also isNull().

### bool Q3PtrVector::fill ( const type * d, int size = -1 )

Inserts item d in all positions in the vector. Any existing items are removed. If d is 0, the vector becomes empty.

If size >= 0, the vector is first resized to size. By default, size is -1.

Returns true if successful, i.e. size is the same as the current size, or size is larger and the memory has successfully been allocated; otherwise returns false.

See also resize(), insert(), and isEmpty().

### int Q3PtrVector::find ( const type * d, uint i = 0 ) const

Finds the first occurrence of item d in the vector using a linear search. The search starts at position i, which must be less than size(). i is by default 0; i.e. the search starts at the start of the vector.

Returns the position of d, or -1 if d could not be found.

Compares items using the virtual function compareItems().

Use the much faster bsearch() to search a sorted vector.

See also findRef() and bsearch().

### int Q3PtrVector::findRef ( const type * d, uint i = 0 ) const

Finds the first occurrence of the item pointer d in the vector using a linear search. The search starts at position i, which must be less than size(). i is by default 0; i.e. the search starts at the start of the vector.

Returns the position of d, or -1 if d could not be found.

This function does not use compareItems() to compare items.

Use the much faster bsearch() to search a sorted vector.

See also find() and bsearch().

### bool Q3PtrVector::insert ( uint i, const type * d )

Sets position i in the vector to contain the item d. i must be less than size(). Any previous element in position i is removed.

Returns true if i is within range; otherwise returns false.

See also at().

### bool Q3PtrVector::isEmpty () const

Returns true if the vector is empty; otherwise returns false.

See also count().

### bool Q3PtrVector::isNull () const

Returns true if the vector is null; otherwise returns false.

A null vector has size() == 0 and data() == 0.

See also size().

### QDataStream & Q3PtrVector::read ( QDataStream & s, Q3PtrCollection::Item & item ) `[virtual protected]`

Reads a vector item, item, from the stream s and returns a reference to the stream.

The default implementation sets item to 0.

See also write().

### bool Q3PtrVector::remove ( uint i )

Removes the item at position i in the vector, if there is one. i must be less than size().

Returns true if i is within range; otherwise returns false.

See also take() and at().

### bool Q3PtrVector::resize ( uint size )

Resizes (expands or shrinks) the vector to size elements. The vector becomes a null vector if size == 0.

Any items at position size or beyond in the vector are removed. New positions are initialized to 0.

Returns true if successful, i.e. if the memory was successfully allocated; otherwise returns false.

See also size() and isNull().

### uint Q3PtrVector::size () const

Returns the size of the vector, i.e. the number of vector positions. This is also the maximum number of items the vector can hold.

The vector is a null vector if size() == 0.

See also isNull(), resize(), and count().

### void Q3PtrVector::sort ()

Sorts the items in ascending order. Any empty positions will be put last.

Compares items using the virtual function compareItems().

See also bsearch().

### type * Q3PtrVector::take ( uint i )

Returns the item at position i in the vector, and removes that item from the vector. i must be less than size(). If there is no item at position i, 0 is returned.

Unlike remove(), this function does not call deleteItem() for the removed item.

See also remove() and at().

### QDataStream & Q3PtrVector::write ( QDataStream & s, Q3PtrCollection::Item item ) const `[virtual protected]`

Writes a vector item, item, to the stream s and returns a reference to the stream.

The default implementation does nothing.

See also read().

### Q3PtrVector<type> & Q3PtrVector::operator= ( const Q3PtrVector<type> & v )

Assigns v to this vector and returns a reference to this vector.

This vector is first cleared and then all the items from v are copied into the vector. Only the pointers are copied (i.e. shallow copy).

See also clear().

### bool Q3PtrVector::operator== ( const Q3PtrVector<type> & v ) const

Returns true if this vector and v are equal; otherwise returns false.

### type * Q3PtrVector::operator[] ( int i ) const

Returns the item at position i, or 0 if there is no item at that position. i must be less than size().

Equivalent to at(i).

See also at().