qmapiterator.3qt

linux下GUI编程工具qt的在线连接帮助手册

'\" t
.TH QMapIterator 3qt "11 October 2001" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2001 Trolltech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QMapIterator \- Iterator for QMap
.PP
\fC#include <qmap.h>\fR
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "typedef std::bidirectional_iterator_tag \fBiterator_category\fR"
.br
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.BI "typedef T \fBvalue_type\fR"
.br
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.BI "typedef T * \fBpointer\fR"
.br
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.BI "typedef T & \fBreference\fR"
.br
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.BI "\fBQMapIterator\fR ()"
.br
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.BI "\fBQMapIterator\fR ( QMapNode<K, T> * p )"
.br
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.BI "\fBQMapIterator\fR ( const QMapIterator<K, T> & it )"
.br
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.BI "bool \fBoperator==\fR ( const QMapIterator<K, T> & it ) const"
.br
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.BI "bool \fBoperator!=\fR ( const QMapIterator<K, T> & it ) const"
.br
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.BI "T & \fBoperator*\fR ()"
.br
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.BI "const T & \fBoperator*\fR () const"
.br
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.BI "const K & \fBkey\fR () const"
.br
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.BI "T & \fBdata\fR ()"
.br
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.BI "const T & \fBdata\fR () const"
.br
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.BI "QMapIterator<K, T> & \fBoperator++\fR ()"
.br
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.BI "QMapIterator<K, T> \fBoperator++\fR ( int )"
.br
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.BI "QMapIterator<K, T> & \fBoperator--\fR ()"
.br
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.BI "QMapIterator<K, T> \fBoperator--\fR ( int )"
.br
.in -1c
.SH DESCRIPTION
The QMapIterator class provides an iterator for QMap.
.PP
You cannot create an iterator by yourself. Instead, you have to ask a map to give you one. An iterator is as big as a pointer; on 32-bit machines that means 4 bytes, on 64-bit ones 8 bytes. That makes copying them very fast. They resemble the semantics of pointers as much as possible, and they are almost as fast as usual pointers. See the QMap example.
.PP
The only way to traverse a map is to use iterators. QMap is highly optimized for performance and memory usage. On the other hand this means that you have to be a bit more careful with what you are doing. QMap does not know about all its iterators, and the iterators don't even know to which map they belong. That makes things fast but a bit dangerous because it is up to you to make sure that the iterators you are using are still valid. QDictIterator will be able to give warnings, whereas QMapIterator may end up in an undefined state.
.PP
For every Iterator there is also a ConstIterator. You have to use the ConstIterator to access a QMap in a const environment or if the reference or pointer to the map is itself const. Its semantics are the same, but it returns only const references to the item it points to.
.PP
See also QMap, QMapConstIterator, Qt Template Library Classes and Non-GUI Classes.
.SS "Member Type Documentation"
.SH "QMapIterator::iterator_category"
The type of iterator category, \fCstd::bidirectional_iterator_tag\fR.
.SH "QMapIterator::pointer"
Pointer to value_type.
.SH "QMapIterator::reference"
Reference to value_type.
.SH "QMapIterator::value_type"
The type of value.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QMapIterator::QMapIterator ()"
Creates an uninitialized iterator.
.SH "QMapIterator::QMapIterator ( QMapNode<K, T> * p )"
Constructs an iterator starting at node \fIp\fR.
.SH "QMapIterator::QMapIterator ( const QMapIterator<K, T> & it )"
Constructs a copy of the iterator, \fIit\fR.
.SH "T & QMapIterator::data ()"
Returns a reference to the current item.
.SH "const T & QMapIterator::data () const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Returns a const reference to the data of the current item.
.SH "const K & QMapIterator::key () const"
Returns a const reference to the data of the current key.
.SH "bool QMapIterator::operator!= ( const QMapIterator<K, T> & it ) const"
Compares the iterator to the \fIit\fR iterator and returns FALSE if they point to the same item; otherwise returns TRUE.
.SH "T & QMapIterator::operator* ()"
Dereference operator. Returns a reference to the current item. The same as data().
.SH "const T & QMapIterator::operator* () const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Dereference operator. Returns a const reference to the current item. The same as data().
.SH "QMapIterator<K, T> & QMapIterator::operator++ ()"
Prefix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator cannot check whether it reached the end of the map. Incrementing the iterator returned by end() causes undefined results.
.SH "QMapIterator<K, T> QMapIterator::operator++ ( int )"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Postfix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator cannot check whether it reached the end of the map. Incrementing the iterator returned by end() causes undefined results.
.SH "QMapIterator<K, T> & QMapIterator::operator-- ()"
Prefix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator cannot check whether it reached the beginning of the map. Decrementing the iterator returned by begin() causes undefined results.
.SH "QMapIterator<K, T> QMapIterator::operator-- ( int )"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Postfix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator cannot check whether it reached the beginning of the map. Decrementing the iterator returned by begin() causes undefined results.
.SH "bool QMapIterator::operator== ( const QMapIterator<K, T> & it ) const"
Compares the iterator to the \fIit\fR iterator and returns TRUE if they
point to the same item; otherwise returns FALSE.

.SH "SEE ALSO"
.BR http://doc.trolltech.com/qmapiterator.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports help us to help you. Thank you.
.P
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with
a web browser. This man page is provided as a convenience for those
users who prefer man pages, although this format is not officially
supported by Trolltech. 
.P
If you find errors in this manual page, please report them to
.BR [e-mail] .
Please include the name of the manual page (qmapiterator.3qt) and the Qt
version (3.0.0).