The QPtrVector class is a template collection class that
provides a vector (array).
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Detailed Description
The QPtrVector class is a template collection class that
provides a vector (array).
QValueVector is an STL-compatible alternative to this class.
QPtrVector is implemented as a template class. Defines a template
instance QPtrVector<X> to create a vector that contains pointers
to X (X*).
A vector is the same as an array. The main difference between
QPtrVector and QMemArray is that QPtrVector stores pointers to the
elements, whereas QMemArray stores the elements themselves (i.e.
QMemArray is value-based and QPtrVector 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 behaviour 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 QMemArray and Non-GUI Classes.
Member Function Documentation
QPtrVector::QPtrVector ()
Constructs a null vector.
See also isNull().
QPtrVector::QPtrVector ( 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().
QPtrVector::QPtrVector ( const QPtrVector<type> & v )
Constructs a copy of v. Only the pointers are copied (i.e.
shallow copy).
QPtrVector::~QPtrVector ()
Removes all items from the vector, and destroys the vector itself.
See also clear().
type * QPtrVector::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().
bool QPtrCollection::autoDelete () const
Returns the setting of the auto-delete option. The default is FALSE.
See also setAutoDelete().
int QPtrVector::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 QPtrVector::clear () [virtual]
Removes all items from the vector, and destroys the vector itself.
The vector becomes a null vector.
See also isNull().
Reimplemented from QPtrCollection.
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 QPtrVector::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 QPtrVector::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 QPtrVector::count () const [virtual]
Returns the number of items in the vector. The vector is empty if
count() == 0.
See also isEmpty(), size(), and isNull().
Reimplemented from QPtrCollection.
type ** QPtrVector::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 QPtrVector::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 QPtrVector::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 QPtrVector::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 QPtrVector::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.
See also at().
bool QPtrVector::isEmpty () const
Returns TRUE if the vector is empty; otherwise returns FALSE.
See also count().
bool QPtrVector::isNull () const
Returns TRUE if the vector is null; otherwise returns FALSE.
A null vector has size() == 0 and data() == 0.
See also size().
QPtrVector<type> & QPtrVector::operator= ( const QPtrVector<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 QPtrVector::operator== ( const QPtrVector<type> & v ) const
Returns TRUE if this vector and v are equal; otherwise returns
FALSE.
type * QPtrVector::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().
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 QPtrVector::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 QPtrVector::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().
void QPtrCollection::setAutoDelete ( bool enable )
Sets the collection to auto-delete its contents if enable is
TRUE and to never delete them if enable is FALSE.
If auto-deleting is turned on, all the items in a collection are
deleted when the collection itself is deleted. This is convenient
if the collection has the only pointer to the items.
The default setting is FALSE, for safety. If you turn it on, be
careful about copying the collection - you might find yourself
with two collections deleting the same items.
Note that the auto-delete setting may also affect other functions
in subclasses. For example, a subclass that has a remove()
function will remove the item from its data structure, and if
auto-delete is enabled, will also delete the item.
See also autoDelete().
Examples: grapher/grapher.cpp, scribble/scribble.cpp, and table/bigtable/main.cpp.
uint QPtrVector::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 QPtrVector::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 * QPtrVector::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().
Writes a vector item, item, to the stream s and returns a
reference to the stream.
The default implementation does nothing.
See also read().
This file is part of the Qt toolkit.
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