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| author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-07-10 15:24:15 -0500 |
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| committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-07-10 15:24:15 -0500 |
| commit | bd0f3345a938b35ce6a12f6150373b0955b8dd12 (patch) | |
| tree | 7a520322212d48ebcb9fbe1087e7fca28b76185c /doc/html/qmap.html | |
| download | qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.tar.gz qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.zip | |
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diff --git a/doc/html/qmap.html b/doc/html/qmap.html new file mode 100644 index 0000000..eefe0a7 --- /dev/null +++ b/doc/html/qmap.html @@ -0,0 +1,574 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/qmap.doc:41 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>QMap Class</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QMap Class Reference</h1> + +<p>The QMap class is a value-based template class that +provides a dictionary. +<a href="#details">More...</a> +<p><tt>#include <<a href="qmap-h.html">qmap.h</a>></tt> +<p><a href="qmap-members.html">List of all member functions.</a> +<h2>Public Members</h2> +<ul> +<li class=fn>typedef Key <a href="#key_type"><b>key_type</b></a></li> +<li class=fn>typedef T <a href="#mapped_type"><b>mapped_type</b></a></li> +<li class=fn>typedef QPair<const key_type, mapped_type> <a href="#value_type"><b>value_type</b></a></li> +<li class=fn>typedef value_type * <a href="#pointer"><b>pointer</b></a></li> +<li class=fn>typedef const value_type * <a href="#const_pointer"><b>const_pointer</b></a></li> +<li class=fn>typedef value_type & <a href="#reference"><b>reference</b></a></li> +<li class=fn>typedef const value_type & <a href="#const_reference"><b>const_reference</b></a></li> +<li class=fn>typedef size_t <a href="#size_type"><b>size_type</b></a></li> +<li class=fn>typedef QMapIterator<Key, T> <a href="#iterator"><b>iterator</b></a></li> +<li class=fn>typedef QMapConstIterator<Key, T> <a href="#const_iterator"><b>const_iterator</b></a></li> +<li class=fn>typedef QPair<iterator, bool> <b>insert_pair</b></li> +<li class=fn>typedef QMapIterator<Key, T> <a href="#Iterator"><b>Iterator</b></a></li> +<li class=fn>typedef QMapConstIterator<Key, T> <a href="#ConstIterator"><b>ConstIterator</b></a></li> +<li class=fn>typedef T <a href="#ValueType"><b>ValueType</b></a></li> +<li class=fn><a href="#QMap"><b>QMap</b></a> ()</li> +<li class=fn><a href="#QMap-2"><b>QMap</b></a> ( const QMap<Key, T> & m )</li> +<li class=fn><a href="#QMap-3"><b>QMap</b></a> ( const std::map<Key, T> & m )</li> +<li class=fn><a href="#~QMap"><b>~QMap</b></a> ()</li> +<li class=fn>QMap<Key, T> & <a href="#operator-eq"><b>operator=</b></a> ( const QMap<Key, T> & m )</li> +<li class=fn>QMap<Key, T> & <a href="#operator-eq-2"><b>operator=</b></a> ( const std::map<Key, T> & m )</li> +<li class=fn>iterator <a href="#begin"><b>begin</b></a> ()</li> +<li class=fn>iterator <a href="#end"><b>end</b></a> ()</li> +<li class=fn>const_iterator <a href="#begin-2"><b>begin</b></a> () const</li> +<li class=fn>const_iterator <a href="#end-2"><b>end</b></a> () const</li> +<li class=fn>const_iterator <a href="#constBegin"><b>constBegin</b></a> () const</li> +<li class=fn>const_iterator <a href="#constEnd"><b>constEnd</b></a> () const</li> +<li class=fn>iterator <a href="#replace"><b>replace</b></a> ( const Key & k, const T & v )</li> +<li class=fn>size_type <a href="#size"><b>size</b></a> () const</li> +<li class=fn>bool <a href="#empty"><b>empty</b></a> () const</li> +<li class=fn>QPair<iterator, bool> <a href="#insert-2"><b>insert</b></a> ( const value_type & x )</li> +<li class=fn>void <a href="#erase"><b>erase</b></a> ( iterator it )</li> +<li class=fn>void <a href="#erase-2"><b>erase</b></a> ( const key_type & k )</li> +<li class=fn>size_type <a href="#count"><b>count</b></a> ( const key_type & k ) const</li> +<li class=fn>T & <a href="#operator[]"><b>operator[]</b></a> ( const Key & k )</li> +<li class=fn>void <a href="#clear"><b>clear</b></a> ()</li> +<li class=fn>iterator <a href="#find"><b>find</b></a> ( const Key & k )</li> +<li class=fn>const_iterator <a href="#find-2"><b>find</b></a> ( const Key & k ) const</li> +<li class=fn>const T & <a href="#operator[]-2"><b>operator[]</b></a> ( const Key & k ) const</li> +<li class=fn>bool <a href="#contains"><b>contains</b></a> ( const Key & k ) const</li> +<li class=fn>size_type <a href="#count-2"><b>count</b></a> () const</li> +<li class=fn>QValueList<Key> <a href="#keys"><b>keys</b></a> () const</li> +<li class=fn>QValueList<T> <a href="#values"><b>values</b></a> () const</li> +<li class=fn>bool <a href="#isEmpty"><b>isEmpty</b></a> () const</li> +<li class=fn>iterator <a href="#insert"><b>insert</b></a> ( const Key & key, const T & value, bool overwrite = TRUE )</li> +<li class=fn>void <a href="#remove"><b>remove</b></a> ( iterator it )</li> +<li class=fn>void <a href="#remove-2"><b>remove</b></a> ( const Key & k )</li> +</ul> +<h2>Protected Members</h2> +<ul> +<li class=fn>void <a href="#detach"><b>detach</b></a> ()</li> +</ul> +<h2>Related Functions</h2> +<ul> +<li class=fn>QDataStream & <a href="#operator-gt-gt"><b>operator>></b></a> ( QDataStream & s, QMap<Key, T> & m )</li> +<li class=fn>QDataStream & <a href="#operator-lt-lt"><b>operator<<</b></a> ( QDataStream & s, const QMap<Key, T> & m )</li> +</ul> +<hr><a name="details"></a><h2>Detailed Description</h2> + + +The QMap class is a value-based template class that +provides a dictionary. +<p> + + + +<p> QMap is a Qt implementation of an STL-like map container. It can +be used in your application if the standard <tt>map</tt> is not +available on all your target platforms. QMap is part of the <a href="qtl.html">Qt Template Library</a>. +<p> QMap<Key, Data> defines a template instance to create a +dictionary with keys of type Key and values of type Data. QMap +does not store pointers to the members of the map; instead, it +holds a copy of every member. For this reason, QMap is +value-based, whereas <a href="qptrlist.html">QPtrList</a> and <a href="qdict.html">QDict</a> are pointer-based. +<p> QMap contains and manages a collection of objects of type Data +with associated key values of type Key and provides iterators that +allow the contained objects to be addressed. QMap owns the +contained items. +<p> Some classes cannot be used within a QMap. For example everything +derived from <a href="qobject.html">QObject</a> and thus all classes that implement widgets. +Only values can be used in a QMap. To qualify as a value, the +class must provide +<p> <ul> +<li> A copy constructor +<li> An assignment operator +<li> A default constructor, i.e. a constructor that does not take +any arguments. +</ul> +<p> Note that C++ defaults to field-by-field assignment operators and +copy constructors if no explicit version is supplied. In many +cases, this is sufficient. +<p> The class used for the key requires that the <tt>operator<</tt> is +implemented to define ordering of the keys. +<p> QMap's function naming is consistent with the other Qt classes +(e.g., <a href="#count">count</a>(), <a href="#isEmpty">isEmpty</a>()). QMap also provides extra functions for +compatibility with STL algorithms, such as <a href="#size">size</a>() and <a href="#empty">empty</a>(). +Programmers already familiar with the STL <tt>map</tt> can use these +the STL-like functions if preferred. +<p> Example: +<a name="qmap-eg"></a> +<pre> + #include <<a href="qstring-h.html">qstring.h</a>> + #include <<a href="qmap-h.html">qmap.h</a>> + #include <<a href="qstring-h.html">qstring.h</a>> + + class Employee + { + public: + Employee(): sn(0) {} + Employee( const <a href="qstring.html">QString</a>& forename, const <a href="qstring.html">QString</a>& surname, int salary ) + : fn(forename), sn(surname), sal(salary) + { } + + <a href="qstring.html">QString</a> forename() const { return fn; } + <a href="qstring.html">QString</a> surname() const { return sn; } + int salary() const { return sal; } + void setSalary( int salary ) { sal = salary; } + + private: + <a href="qstring.html">QString</a> fn; + <a href="qstring.html">QString</a> sn; + int sal; + }; + + int main(int argc, char **argv) + { + <a href="qapplication.html">QApplication</a> app( argc, argv ); + + typedef QMap<QString, Employee> EmployeeMap; + EmployeeMap map; + + map["JD001"] = Employee("John", "Doe", 50000); + map["JW002"] = Employee("Jane", "Williams", 80000); + map["TJ001"] = Employee("Tom", "Jones", 60000); + + Employee sasha( "Sasha", "Hind", 50000 ); + map["SH001"] = sasha; + sasha.setSalary( 40000 ); + + EmployeeMap::<a href="#Iterator">Iterator</a> it; + for ( it = map.begin(); it != map.end(); ++it ) { + printf( "%s: %s, %s earns %d\n", + it.key().latin1(), + it.data().surname().latin1(), + it.data().forename().latin1(), + it.data().salary() ); + } + return 0; + } + </pre> + +<p> Program output: +<pre> + JD001: Doe, John earns 50000 + JW002: Williams, Jane earns 80000 + SH001: Hind, Sasha earns 50000 + TJ001: Jones, Tom earns 60000 + </pre> + +<p> The latest changes to Sasha's salary did not affect the value in +the list because the map created a copy of Sasha's entry. In +addition, notice that the items are sorted alphabetically (by key) +when iterating over the map. +<p> There are several ways to find items in a map. The <a href="#begin">begin</a>() and +<a href="#end">end</a>() functions return iterators to the beginning and end of the +map. The advantage of using an iterator is that you can move +forward or backward by incrementing/decrementing the iterator. +The iterator returned by end() points to the element which is one +past the last element in the container. The past-the-end iterator +is still associated with the map it belongs to, however it is <em>not</em> dereferenceable; <a href="qsize.html#operator*-4">operator*</a>() will not return a well-defined +value. If the map is empty, the iterator returned by begin() will +equal the iterator returned by end(). +<p> Another way to find an element in the map is by using the <a href="#find">find</a>() +function. This returns an iterator pointing to the desired item or +to the end() iterator if no such element exists. +<p> Another approach uses the operator[]. But be warned: if the map +does not contain an entry for the element you are looking for, +operator[] inserts a default value. If you do not know that the +element you are searching for is really in the list, you should +not use operator[]. The following example illustrates this: +<p> <pre> + QMap<QString,QString> map; + map["Clinton"] = "Bill"; + str << map["Clinton"] << map["Bush"] << endl; + </pre> + +<p> The code fragment will print out "Clinton", "". Since the value +associated with the "Bush" key did not exist, the map inserted a +default value (in this case, an empty string). If you are not +sure whether a certain element is in the map, you should use +find() and iterators instead. +<p> If you just want to know whether a certain key is contained in the +map, use the <a href="#contains">contains</a>() function. In addition, <a href="#count">count</a>() tells you +how many keys are in the map. +<p> It is safe to have multiple iterators at the same time. If some +member of the map is removed, only iterators pointing to the +removed member become invalid; inserting in the map does not +invalidate any iterators. +<p> Since QMap is value-based, there is no need to be concerned about +deleting items in the map. The map holds its own copies and will +free them if the corresponding member or the map itself is +deleted. +<p> QMap is <a href="shclass.html#implicitly-shared">implicitly shared</a>. This means you can just make copies of +the map in time O(1). If multiple QMap instances share the same +data and one is modifying the map's data, this modifying instance +makes a copy and modifies its private copy: so it does not affect +other instances. If a QMap is being used in a multi-threaded +program, you must protect all access to the map. See <a href="qmutex.html">QMutex</a>. +<p> There are a couple of ways of inserting new items into the map. +One uses the <a href="#insert">insert</a>() method; the other uses operator[]: +<pre> + QMap<QString, QString> map; + map["Clinton"] = "Bill"; + map.<a href="#insert">insert</a>( "Bush", "George" ); + </pre> + +<p> Items can also be removed from the map in several ways. One way is +to pass an iterator to <a href="#remove">remove</a>(). Another way is to pass a key +value to remove(), which will delete the entry with the requested +key. In addition you can clear the entire map using the <a href="#clear">clear</a>() +method. +<p> <p>See also <a href="qmapiterator.html">QMapIterator</a>, <a href="qtl.html">Qt Template Library Classes</a>, <a href="shared.html">Implicitly and Explicitly Shared Classes</a>, and <a href="tools.html">Non-GUI Classes</a>. + +<hr><h2>Member Type Documentation</h2> +<h3 class=fn><a name="ConstIterator"></a>QMap::ConstIterator</h3> +The map's const iterator type, Qt style. +<h3 class=fn><a name="Iterator"></a>QMap::Iterator</h3> +The map's iterator type, Qt style. +<h3 class=fn><a name="ValueType"></a>QMap::ValueType</h3> +Corresponds to <a href="qpair.html">QPair</a><key_type, mapped_type>, Qt style. +<h3 class=fn><a name="const_iterator"></a>QMap::const_iterator</h3> +The map's const iterator type. +<h3 class=fn><a name="const_pointer"></a>QMap::const_pointer</h3> +Const pointer to value_type. +<h3 class=fn><a name="const_reference"></a>QMap::const_reference</h3> +Const reference to value_type. +<h3 class=fn><a name="iterator"></a>QMap::iterator</h3> +The map's iterator type. +<h3 class=fn><a name="key_type"></a>QMap::key_type</h3> +The map's key type. +<h3 class=fn><a name="mapped_type"></a>QMap::mapped_type</h3> +The map's data type. +<h3 class=fn><a name="pointer"></a>QMap::pointer</h3> +Pointer to value_type. +<h3 class=fn><a name="reference"></a>QMap::reference</h3> +Reference to value_type. +<h3 class=fn><a name="size_type"></a>QMap::size_type</h3> +An unsigned integral type, used to represent various sizes. +<h3 class=fn><a name="value_type"></a>QMap::value_type</h3> +Corresponds to <a href="qpair.html">QPair</a><key_type, mapped_type>. +<hr><h2>Member Function Documentation</h2> +<h3 class=fn><a name="QMap"></a>QMap::QMap () +</h3> + +<p> Constructs an empty map. + +<h3 class=fn><a name="QMap-2"></a>QMap::QMap ( const <a href="qmap.html">QMap</a><Key, T> & m ) +</h3> + +<p> Constructs a copy of <em>m</em>. +<p> This operation costs O(1) time because QMap is <a href="shclass.html#implicitly-shared">implicitly shared</a>. +This makes returning a QMap from a function very fast. If a shared +instance is modified, it will be copied (copy-on-write), and this +takes O(n) time. + +<h3 class=fn><a name="QMap-3"></a>QMap::QMap ( const std::map<Key, T> & m ) +</h3> + +<p> Constructs a copy of <em>m</em>. + +<h3 class=fn><a name="~QMap"></a>QMap::~QMap () +</h3> + +<p> Destroys the map. References to the values in the map and all +iterators of this map become invalidated. Since QMap is highly +tuned for performance you won't see warnings if you use invalid +iterators, because it is not possible for an iterator to check +whether it is valid or not. + +<h3 class=fn><a href="qmap.html#iterator">iterator</a> <a name="begin"></a>QMap::begin () +</h3> + +<p> Returns an iterator pointing to the first element in the map. This +iterator equals <a href="#end">end</a>() if the map is empty. +<p> The items in the map are traversed in the order defined by +operator<(Key, Key). +<p> <p>See also <a href="#end">end</a>() and <a href="qmapiterator.html">QMapIterator</a>. + +<h3 class=fn><a href="qmap.html#const_iterator">const_iterator</a> <a name="begin-2"></a>QMap::begin () const +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> <p>See also <a href="#end">end</a>() and <a href="qmapconstiterator.html">QMapConstIterator</a>. + +<h3 class=fn>void <a name="clear"></a>QMap::clear () +</h3> + +<p> Removes all items from the map. +<p> <p>See also <a href="#remove">remove</a>(). + +<h3 class=fn><a href="qmap.html#const_iterator">const_iterator</a> <a name="constBegin"></a>QMap::constBegin () const +</h3> + +<p> Returns an iterator pointing to the first element in the map. This +iterator equals <a href="#end">end</a>() if the map is empty. +<p> The items in the map are traversed in the order defined by +operator<(Key, Key). +<p> <p>See also <a href="#constEnd">constEnd</a>() and <a href="qmapconstiterator.html">QMapConstIterator</a>. + +<h3 class=fn><a href="qmap.html#const_iterator">const_iterator</a> <a name="constEnd"></a>QMap::constEnd () const +</h3> + +<p> The iterator returned by <a href="#end">end</a>() points to the element which is one +past the last element in the container. The past-the-end iterator +is still associated with the map it belongs to, but it is <em>not</em> +dereferenceable; <a href="qsize.html#operator*-4">operator*</a>() will not return a well-defined value. +<p> This iterator equals <a href="#constBegin">constBegin</a>() if the map is empty. +<p> <p>See also <a href="#constBegin">constBegin</a>() and <a href="qmapconstiterator.html">QMapConstIterator</a>. + +<h3 class=fn>bool <a name="contains"></a>QMap::contains ( const Key & k ) const +</h3> + +<p> Returns TRUE if the map contains an item with key <em>k</em>; otherwise +returns FALSE. + +<h3 class=fn><a href="qmap.html#size_type">size_type</a> <a name="count"></a>QMap::count ( const <a href="qmap.html#key_type">key_type</a> & k ) const +</h3> + +<p> Returns the number of items whose key is <em>k</em>. Since QMap does not +allow duplicate keys, the return value is always 0 or 1. +<p> This function is provided for STL compatibility. + +<h3 class=fn><a href="qmap.html#size_type">size_type</a> <a name="count-2"></a>QMap::count () const +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Returns the number of items in the map. +<p> <p>See also <a href="#isEmpty">isEmpty</a>(). + +<h3 class=fn>void <a name="detach"></a>QMap::detach ()<tt> [protected]</tt> +</h3> + +<p> If the map does not share its data with another QMap instance, +nothing happens; otherwise the function creates a new copy of this +map and detaches from the shared one. This function is called +whenever the map is modified. The <a href="shclass.html#implicit-sharing">implicit sharing</a> mechanism is +implemented this way. + +<h3 class=fn>bool <a name="empty"></a>QMap::empty () const +</h3> + +<p> Returns TRUE if the map contains no items; otherwise returns +FALSE. +<p> This function is provided for STL compatibility. It is equivalent +to <a href="#isEmpty">isEmpty</a>(). +<p> <p>See also <a href="#size">size</a>(). + +<h3 class=fn><a href="qmap.html#iterator">iterator</a> <a name="end"></a>QMap::end () +</h3> + +<p> The iterator returned by <a href="#end">end</a>() points to the element which is one +past the last element in the container. The past-the-end iterator +is still associated with the map it belongs to, but it is <em>not</em> +dereferenceable; <a href="qsize.html#operator*-4">operator*</a>() will not return a well-defined value. +<p> This iterator equals <a href="#begin">begin</a>() if the map is empty. +<p> <p>See also <a href="#begin">begin</a>() and <a href="qmapiterator.html">QMapIterator</a>. + +<h3 class=fn><a href="qmap.html#const_iterator">const_iterator</a> <a name="end-2"></a>QMap::end () const +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> +<h3 class=fn>void <a name="erase"></a>QMap::erase ( <a href="qmap.html#iterator">iterator</a> it ) +</h3> + +<p> Removes the item associated with the iterator <em>it</em> from the map. +<p> This function is provided for STL compatibility. It is equivalent +to <a href="#remove">remove</a>(). +<p> <p>See also <a href="#clear">clear</a>(). + +<h3 class=fn>void <a name="erase-2"></a>QMap::erase ( const <a href="qmap.html#key_type">key_type</a> & k ) +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Removes the item with the key <em>k</em> from the map. + +<h3 class=fn><a href="qmap.html#iterator">iterator</a> <a name="find"></a>QMap::find ( const Key & k ) +</h3> + +<p> Returns an iterator pointing to the element with key <em>k</em> in the +map. +<p> Returns <a href="#end">end</a>() if no key matched. +<p> <p>See also <a href="qmapiterator.html">QMapIterator</a>. + +<h3 class=fn><a href="qmap.html#const_iterator">const_iterator</a> <a name="find-2"></a>QMap::find ( const Key & k ) const +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Returns an iterator pointing to the element with key <em>k</em> in the +map. +<p> Returns <a href="#end">end</a>() if no key matched. +<p> <p>See also <a href="qmapconstiterator.html">QMapConstIterator</a>. + +<h3 class=fn><a href="qmap.html#iterator">iterator</a> <a name="insert"></a>QMap::insert ( const Key & key, const T & value, bool overwrite = TRUE ) +</h3> + +<p> Inserts a new item with the key, <em>key</em>, and a value of <em>value</em>. +If there is already an item whose key is <em>key</em>, that item's value +is replaced with <em>value</em>, unless <em>overwrite</em> is FALSE (it is +TRUE by default). In this case an iterator to this item is +returned, else an iterator to the new item is returned. +<p> +<h3 class=fn><a href="qpair.html">QPair</a><iterator, bool> <a name="insert-2"></a>QMap::insert ( const <a href="qmap.html#value_type">value_type</a> & x ) +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Inserts the (key, value) pair <em>x</em> into the map. <em>x</em> is a <a href="qpair.html">QPair</a> +whose <tt>first</tt> element is a key to be inserted and whose <tt>second</tt> +element is the associated value to be inserted. Returns a pair +whose <tt>first</tt> element is an iterator pointing to the inserted +item and whose <tt>second</tt> element is a bool indicating TRUE if <em>x</em> +was inserted and FALSE if it was not inserted, e.g. because it was +already present. +<p> <p>See also <a href="#replace">replace</a>(). + +<h3 class=fn>bool <a name="isEmpty"></a>QMap::isEmpty () const +</h3> + +<p> Returns TRUE if the map contains no items; otherwise returns +FALSE. +<p> <p>See also <a href="#count">count</a>(). + +<h3 class=fn><a href="qvaluelist.html">QValueList</a><Key> <a name="keys"></a>QMap::keys () const +</h3> + +<p> Returns a list of all the keys in the map, in order. + +<h3 class=fn><a href="qmap.html">QMap</a><Key, T> & <a name="operator-eq"></a>QMap::operator= ( const <a href="qmap.html">QMap</a><Key, T> & m ) +</h3> + +<p> Assigns <em>m</em> to this map and returns a reference to this map. +<p> All iterators of the current map become invalidated by this +operation. The cost of such an assignment is O(1), because QMap is +<a href="shclass.html#implicitly-shared">implicitly shared</a>. + +<h3 class=fn><a href="qmap.html">QMap</a><Key, T> & <a name="operator-eq-2"></a>QMap::operator= ( const std::map<Key, T> & m ) +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Assigns <em>m</em> to this map and returns a reference to this map. +<p> All iterators of the current map become invalidated by this +operation. + +<h3 class=fn>T & <a name="operator[]"></a>QMap::operator[] ( const Key & k ) +</h3> + +<p> Returns the value associated with the key <em>k</em>. If no such key is +present, an empty item is inserted with this key and a reference +to the empty item is returned. +<p> You can use this operator both for reading and writing: +<pre> + QMap<QString, QString> map; + map["Clinton"] = "Bill"; + stream << map["Clinton"]; + </pre> + + +<h3 class=fn>const T & <a name="operator[]-2"></a>QMap::operator[] ( const Key & k ) const +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> <b>Warning:</b> This function differs from the non-const version of the +same function. It will <em>not</em> insert an empty value if the key <em>k</em> does not exist. This may lead to logic errors in your program. +You should check if the element exists before calling this +function. +<p> Returns the value associated with the key <em>k</em>. If no such key is +present, a reference to an empty item is returned. + +<h3 class=fn>void <a name="remove"></a>QMap::remove ( <a href="qmap.html#iterator">iterator</a> it ) +</h3> + +<p> Removes the item associated with the iterator <em>it</em> from the map. +<p> <p>See also <a href="#clear">clear</a>(). + +<h3 class=fn>void <a name="remove-2"></a>QMap::remove ( const Key & k ) +</h3> + +<p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Removes the item with the key <em>k</em> from the map. + +<h3 class=fn><a href="qmap.html#iterator">iterator</a> <a name="replace"></a>QMap::replace ( const Key & k, const T & v ) +</h3> + +<p> Replaces the value of the element with key <em>k</em>, with the value <em>v</em>. +<p> <p>See also <a href="#insert">insert</a>() and <a href="#remove">remove</a>(). + +<h3 class=fn><a href="qmap.html#size_type">size_type</a> <a name="size"></a>QMap::size () const +</h3> + +<p> Returns the number of items in the map. +<p> This function is provided for STL compatibility. It is equivalent +to <a href="#count">count</a>(). +<p> <p>See also <a href="#empty">empty</a>(). + +<h3 class=fn><a href="qvaluelist.html">QValueList</a><T> <a name="values"></a>QMap::values () const +</h3> + +<p> Returns a list of all the values in the map, in key order. + +<hr><h2>Related Functions</h2> +<h3 class=fn><a href="qdatastream.html">QDataStream</a> & <a name="operator-lt-lt"></a>operator<< ( <a href="qdatastream.html">QDataStream</a> & s, const <a href="qmap.html">QMap</a><Key, T> & m ) +</h3> + +<p> +<p> Writes the map <em>m</em> to the stream <em>s</em>. The types <em>Key</em> and <em>T</em> +must implement the streaming operator as well. + +<h3 class=fn><a href="qdatastream.html">QDataStream</a> & <a name="operator-gt-gt"></a>operator>> ( <a href="qdatastream.html">QDataStream</a> & s, <a href="qmap.html">QMap</a><Key, T> & m ) +</h3> + +<p> +<p> Reads the map <em>m</em> from the stream <em>s</em>. The types <em>Key</em> and <em>T</em> +must implement the streaming operator as well. + +<!-- eof --> +<hr><p> +This file is part of the <a href="index.html">Qt toolkit</a>. +Copyright © 1995-2007 +<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>Qt 3.3.8</div> +</table></div></address></body> +</html> |