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# QPtrStack Class Reference

The QPtrStack class is a template class that provides a stack. More...

`#include <qptrstack.h>`

List of all member functions.

## Public Members

- QPtrStack ()
- QPtrStack ( const QPtrStack<type> & s )
- ~QPtrStack ()
- QPtrStack<type> & operator= ( const QPtrStack<type> & s )
- bool autoDelete () const
- void setAutoDelete ( bool enable )
- uint count () const
- bool isEmpty () const
- void push ( const type * d )
- type * pop ()
- bool remove ()
- void clear ()
- type * top () const
- operator type * () const
- type * current () const

## Protected Members

- virtual QDataStream & read ( QDataStream & s, QPtrCollection::Item & item )
- virtual QDataStream & write ( QDataStream & s, QPtrCollection::Item item ) const

## Detailed Description

The QPtrStack class is a template class that provides a stack.

QValueStack is an STL-compatible alternative to this class.

Define a template instance QPtrStack<X> to create a stack that operates on pointers to X, (X*).

A stack is a last in, first out (LIFO) structure. Items are added to the top of the stack with push() and retrieved from the top with pop(). Use top() to get a reference to the top element without changing the stack.

You can control the stack's deletion policy with setAutoDelete().

For compatibility with the QPtrCollection classes current() and remove() are provided; they both operate on the top().

See also QPtrList, QPtrQueue, and Non-GUI Classes.

## Member Function Documentation

### QPtrStack::QPtrStack ()

Creates an empty stack.

### QPtrStack::QPtrStack ( const QPtrStack<type> & s )

Creates a stack by making a shallow copy of another stack s.

### QPtrStack::~QPtrStack ()

Destroys the stack. All items will be deleted if autoDelete() is TRUE.

### bool QPtrStack::autoDelete () const

The same as QPtrCollection::autoDelete().

See also setAutoDelete().

### void QPtrStack::clear ()

Removes all items from the stack, deleting them if autoDelete() is TRUE.

See also remove().

### uint QPtrStack::count () const

Returns the number of items in the stack.

See also isEmpty().

### type * QPtrStack::current () const

Returns a pointer to the top item on the stack (most recently pushed). The stack is not changed. Returns 0 if the stack is empty.

### bool QPtrStack::isEmpty () const

Returns TRUE is the stack contains no elements; otherwise returns FALSE.

### QPtrStack::operator type * () const

Returns a pointer to the top item on the stack (most recently pushed). The stack is not changed. Returns 0 if the stack is empty.

### QPtrStack<type> & QPtrStack::operator= ( const QPtrStack<type> & s )

Sets the contents of this stack by making a shallow copy of another stack s. Elements currently in this stack will be deleted if autoDelete() is TRUE.

### type * QPtrStack::pop ()

Removes the top item from the stack and returns it. The stack must not be empty.

### void QPtrStack::push ( const type * d )

Adds an element d to the top of the stack. Last in, first out.

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

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

The default implementation sets item to 0.

See also write().

### bool QPtrStack::remove ()

Removes the top item from the stack and deletes it if autoDelete() is TRUE. Returns TRUE if there was an item to pop; otherwise returns FALSE.

See also clear().

### void QPtrStack::setAutoDelete ( bool enable )

Defines whether this stack auto-deletes its contents. The same as QPtrCollection::setAutoDelete().

If enable is TRUE the stack auto-deletes its contents; if enable is FALSE the stack does not delete its contents.

See also autoDelete().

### type * QPtrStack::top () const

Returns a pointer to the top item on the stack (most recently pushed). The stack is not changed. Returns 0 if the stack is empty.

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

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

The default implementation does nothing.

See also read().

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