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316 lines
10 KiB
316 lines
10 KiB
'\" t
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.TH QPtrDict 3qt "2 February 2007" "Trolltech AS" \" -*- nroff -*-
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.\" Copyright 1992-2007 Trolltech ASA. All rights reserved. See the
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.\" license file included in the distribution for a complete license
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.\" statement.
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.\"
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.ad l
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.nh
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.SH NAME
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QPtrDict \- Template class that provides a dictionary based on void* keys
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.SH SYNOPSIS
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\fC#include <ntqptrdict.h>\fR
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.PP
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Inherits QPtrCollection.
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.PP
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.SS "Public Members"
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.in +1c
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.ti -1c
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.BI "\fBQPtrDict\fR ( int size = 17 )"
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.br
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.ti -1c
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.BI "\fBQPtrDict\fR ( const QPtrDict<type> & dict )"
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.br
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.ti -1c
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.BI "\fB~QPtrDict\fR ()"
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.br
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.ti -1c
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.BI "QPtrDict<type> & \fBoperator=\fR ( const QPtrDict<type> & dict )"
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.br
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.ti -1c
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.BI "virtual uint \fBcount\fR () const"
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.br
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.ti -1c
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.BI "uint \fBsize\fR () const"
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.br
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.ti -1c
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.BI "bool \fBisEmpty\fR () const"
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.br
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.ti -1c
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.BI "void \fBinsert\fR ( void * key, const type * item )"
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.br
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.ti -1c
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.BI "void \fBreplace\fR ( void * key, const type * item )"
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.br
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.ti -1c
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.BI "bool \fBremove\fR ( void * key )"
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.br
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.ti -1c
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.BI "type * \fBtake\fR ( void * key )"
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.br
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.ti -1c
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.BI "type * \fBfind\fR ( void * key ) const"
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.br
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.ti -1c
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.BI "type * \fBoperator[]\fR ( void * key ) const"
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.br
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.ti -1c
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.BI "virtual void \fBclear\fR ()"
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.br
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.ti -1c
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.BI "void \fBresize\fR ( uint newsize )"
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.br
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.ti -1c
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.BI "void \fBstatistics\fR () const"
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.br
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.in -1c
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.SS "Important Inherited Members"
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.in +1c
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.ti -1c
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.BI "bool \fBautoDelete\fR () const"
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.br
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.ti -1c
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.BI "void \fBsetAutoDelete\fR ( bool enable )"
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.br
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.in -1c
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.SS "Protected Members"
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.in +1c
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.ti -1c
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.BI "virtual QDataStream & \fBread\fR ( QDataStream & s, QPtrCollection::Item & item )"
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.br
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.ti -1c
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.BI "virtual QDataStream & \fBwrite\fR ( QDataStream & s, QPtrCollection::Item ) const"
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.br
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.in -1c
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.SH DESCRIPTION
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The QPtrDict class is a template class that provides a dictionary based on void* keys.
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.PP
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QPtrDict is implemented as a template class. Define a template instance QPtrDict<X> to create a dictionary that operates on pointers to X (X*).
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.PP
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A dictionary is a collection of key-value pairs. The key is a void* used for insertion, removal and lookup. The value is a pointer. Dictionaries provide very fast insertion and lookup.
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.PP
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Example:
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.PP
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.nf
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.br
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QPtrDict<char> fields; // void* keys, char* values
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.br
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.br
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QLineEdit *le1 = new QLineEdit( this );
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.br
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le1->setText( "Simpson" );
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.br
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QLineEdit *le2 = new QLineEdit( this );
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.br
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le2->setText( "Homer" );
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.br
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QLineEdit *le3 = new QLineEdit( this );
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.br
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le3->setText( "45" );
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.br
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.br
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fields.insert( le1, "Surname" );
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.br
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fields.insert( le2, "Forename" );
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.br
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fields.insert( le3, "Age" );
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.br
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.br
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QPtrDictIterator<char> it( fields );
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.br
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for( ; it.current(); ++it )
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.br
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cout << it.current() << endl;
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.br
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cout << endl;
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.br
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.br
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if ( fields[le1] ) // Prints "Surname: Simpson"
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.br
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cout << fields[le1] << ": " << le1->text() << endl;
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.br
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.br
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if ( fields[le2] ) // Prints "Forename: Homer"
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.br
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cout << fields[le2] << ": " << le2->text() << endl;
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.br
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.br
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.br
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fields.remove( le1 ); // Removes le1 from the dictionary
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.br
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cout << le1->text() << endl; // Prints "Simpson"
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.br
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.fi
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In this example we use a dictionary to add an extra property (a char*) to the line edits we're using.
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.PP
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See QDict for full details, including the choice of dictionary size, and how deletions are handled.
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.PP
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See also QPtrDictIterator, QDict, QAsciiDict, QIntDict, Collection Classes, Collection Classes, and Non-GUI Classes.
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.SH MEMBER FUNCTION DOCUMENTATION
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.SH "QPtrDict::QPtrDict ( int size = 17 )"
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Constructs a dictionary using an internal hash array with the size \fIsize\fR.
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.PP
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Setting \fIsize\fR to a suitably large prime number (equal to or greater than the expected number of entries) makes the hash distribution better and improves lookup performance.
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.SH "QPtrDict::QPtrDict ( const QPtrDict<type> & dict )"
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Constructs a copy of \fIdict\fR.
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.PP
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Each item in \fIdict\fR is inserted into this dictionary. Only the pointers are copied (shallow copy).
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.SH "QPtrDict::~QPtrDict ()"
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Removes all items from the dictionary and destroys it.
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.PP
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All iterators that access this dictionary will be reset.
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.PP
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See also setAutoDelete().
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.SH "bool QPtrCollection::autoDelete () const"
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Returns the setting of the auto-delete option. The default is FALSE.
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.PP
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See also setAutoDelete().
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.SH "void QPtrDict::clear ()\fC [virtual]\fR"
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Removes all items from the dictionary.
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.PP
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The removed items are deleted if auto-deletion is enabled.
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.PP
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All dictionary iterators that access this dictionary will be reset.
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.PP
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See also remove(), take(), and setAutoDelete().
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.PP
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Reimplemented from QPtrCollection.
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.SH "uint QPtrDict::count () const\fC [virtual]\fR"
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Returns the number of items in the dictionary.
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.PP
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See also isEmpty().
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.PP
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Reimplemented from QPtrCollection.
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.SH "type * QPtrDict::find ( void * key ) const"
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Returns the item associated with \fIkey\fR, or 0 if the key does not exist in the dictionary.
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.PP
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If there are two or more items with equal keys, then the most recently inserted item will be found.
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.PP
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Equivalent to operator[].
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.PP
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See also operator[]().
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.SH "void QPtrDict::insert ( void * key, const type * item )"
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Inserts the \fIkey\fR with the \fIitem\fR into the dictionary.
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.PP
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Multiple items can have the same key, in which case only the last item will be accessible using operator[]().
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.PP
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\fIitem\fR may not be 0.
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.PP
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See also replace().
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.SH "bool QPtrDict::isEmpty () const"
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Returns TRUE if the dictionary is empty; otherwise returns FALSE.
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.PP
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See also count().
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.SH "QPtrDict<type> & QPtrDict::operator= ( const QPtrDict<type> & dict )"
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Assigns \fIdict\fR to this dictionary and returns a reference to this dictionary.
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.PP
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This dictionary is first cleared and then each item in \fIdict\fR is inserted into the dictionary. Only the pointers are copied (shallow copy), unless newItem() has been reimplemented.
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.SH "type * QPtrDict::operator[] ( void * key ) const"
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Returns the item associated with \fIkey\fR, or 0 if the key does not exist in the dictionary.
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.PP
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If there are two or more items with equal keys, then the most recently inserted item will be found.
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.PP
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Equivalent to the find() function.
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.PP
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See also find().
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.SH "QDataStream & QPtrDict::read ( QDataStream & s, QPtrCollection::Item & item )\fC [virtual protected]\fR"
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Reads a dictionary item from the stream \fIs\fR and returns a reference to the stream.
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.PP
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The default implementation sets \fIitem\fR to 0.
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.PP
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See also write().
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.SH "bool QPtrDict::remove ( void * key )"
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Removes the item associated with \fIkey\fR from the dictionary. Returns TRUE if successful, i.e. if \fIkey\fR is in the dictionary; otherwise returns FALSE.
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.PP
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If there are two or more items with equal keys, then the most recently inserted item will be removed.
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.PP
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The removed item is deleted if auto-deletion is enabled.
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.PP
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All dictionary iterators that refer to the removed item will be set to point to the next item in the dictionary traversal order.
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.PP
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See also take(), clear(), and setAutoDelete().
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.SH "void QPtrDict::replace ( void * key, const type * item )"
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If the dictionary has key \fIkey\fR, this key's item is replaced with \fIitem\fR. If the dictionary doesn't contain key \fIkey\fR, \fIitem\fR is inserted into the dictionary using key \fIkey\fR.
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.PP
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\fIitem\fR may not be 0.
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.PP
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Equivalent to
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.PP
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.nf
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.br
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QPtrDict<ItemType> dict;
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.br
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...
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.br
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if ( dict.find( key ) )
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.br
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dict.remove( key );
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.br
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dict.insert( key, item );
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.br
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.fi
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.PP
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If there are two or more items with equal keys, then the most recently inserted item will be replaced.
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.PP
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See also insert().
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.SH "void QPtrDict::resize ( uint newsize )"
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Changes the size of the hash table to \fInewsize\fR. The contents of the dictionary are preserved, but all iterators on the dictionary become invalid.
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.SH "void QPtrCollection::setAutoDelete ( bool enable )"
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Sets the collection to auto-delete its contents if \fIenable\fR is TRUE and to never delete them if \fIenable\fR is FALSE.
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.PP
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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.
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.PP
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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.
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.PP
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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.
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.PP
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See also autoDelete().
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.PP
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Examples:
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.)l grapher/grapher.cpp, scribble/scribble.cpp, and table/bigtable/main.cpp.
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.SH "uint QPtrDict::size () const"
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Returns the size of the internal hash table (as specified in the constructor).
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.PP
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See also count().
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.SH "void QPtrDict::statistics () const"
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Debugging-only function that prints out the dictionary distribution using tqDebug().
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.SH "type * QPtrDict::take ( void * key )"
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Takes the item associated with \fIkey\fR out of the dictionary without deleting it (even if auto-deletion is enabled).
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.PP
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If there are two or more items with equal keys, then the most recently inserted item will be removed.
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.PP
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Returns a pointer to the item taken out, or 0 if the key does not exist in the dictionary.
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.PP
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All dictionary iterators that refer to the taken item will be set to point to the next item in the dictionary traversal order.
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.PP
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See also remove(), clear(), and setAutoDelete().
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.SH "QDataStream & QPtrDict::write ( QDataStream & s, QPtrCollection::Item ) const\fC [virtual protected]\fR"
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Writes a dictionary item to the stream \fIs\fR and returns a reference to the stream.
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.PP
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See also read().
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.SH "SEE ALSO"
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.BR http://doc.trolltech.com/ntqptrdict.html
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.BR http://www.trolltech.com/faq/tech.html
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.SH COPYRIGHT
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Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
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license file included in the distribution for a complete license
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statement.
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.SH AUTHOR
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Generated automatically from the source code.
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.SH BUGS
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If you find a bug in Qt, please report it as described in
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.BR http://doc.trolltech.com/bughowto.html .
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Good bug reports help us to help you. Thank you.
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.P
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The definitive TQt documentation is provided in HTML format; it is
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located at $TQTDIR/doc/html and can be read using TQt Assistant or with
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a web browser. This man page is provided as a convenience for those
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users who prefer man pages, although this format is not officially
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supported by Trolltech.
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.P
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If you find errors in this manual page, please report them to
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.BR qt-bugs@trolltech.com .
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Please include the name of the manual page (tqptrdict.3qt) and the Qt
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version (3.3.8).
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