# Q3PtrVector Class

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

Header: | #include <Q3PtrVector> |

Inherits: | Q3PtrCollection |

## Public Functions

Q3PtrVector() | |

Q3PtrVector(uint size) | |

Q3PtrVector(const Q3PtrVector<type> & v) | |

~Q3PtrVector() | |

type * | at(uint i) const |

int | bsearch(const type * d) const |

uint | contains(const type * d) const |

uint | containsRef(const type * d) 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 |

## Reimplemented Public Functions

- 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().

`[virtual] `

void Q3PtrVector::clear()

Reimplemented from Q3PtrCollection::clear().

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

The vector becomes a null vector.

**See also **isNull().

`[virtual protected] `

int Q3PtrVector::compareItems(Q3PtrCollection::Item* d1*, Q3PtrCollection::Item* d2*)

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().

`[virtual] `

uint Q3PtrVector::count() const

Reimplemented from Q3PtrCollection::count().

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

**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().

`[virtual protected] `

QDataStream & Q3PtrVector::read(QDataStream &* s*, Q3PtrCollection::Item &* item*)

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.

### 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.

### 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.

`[virtual protected] `

QDataStream & Q3PtrVector::write(QDataStream &* s*, Q3PtrCollection::Item* item*) const

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().

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