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| author | Timothy Pearson <[email protected]> | 2011-07-10 15:24:15 -0500 |
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| committer | Timothy Pearson <[email protected]> | 2011-07-10 15:24:15 -0500 |
| commit | bd0f3345a938b35ce6a12f6150373b0955b8dd12 (patch) | |
| tree | 7a520322212d48ebcb9fbe1087e7fca28b76185c /doc/html/collection.html | |
| download | qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.tar.gz qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.zip | |
Add Qt3 development HEAD version
Diffstat (limited to 'doc/html/collection.html')
| -rw-r--r-- | doc/html/collection.html | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/doc/html/collection.html b/doc/html/collection.html new file mode 100644 index 0000000..842ee4b --- /dev/null +++ b/doc/html/collection.html @@ -0,0 +1,250 @@ +<!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/collect.doc:36 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Collection Classes</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>Collection Classes</h1> + + + +<p> <!-- index collection classes --><a name="collection-classes"></a><!-- index persistent data --><a name="persistent-data"></a> +<p> A collection class is a container which holds a number of items in a +data structure and provides various operations to manipulate the +contents of the collection, such as insert item, remove item, find +item, etc. +<p> Qt has several value-based and several pointer-based collection +classes. The pointer-based collection classes work with pointers to +items, while the value-based classes store copies of their items. The +value-based collections are very similar to STL container classes, and +can be used with STL algorithms and containers. See the <a href="qt-template-lib.html">Qt Template Library</a> documentation for +details. +<p> The value-based collections are: +<ul> +<li> <a href="qvaluelist.html">QValueList</a>, a value-based list. +<li> <a href="qvaluevector.html">QValueVector</a>, a value-based vector. +<li> <a href="qvaluestack.html">QValueStack</a>, a value-based stack. +<li> <a href="qmap.html">QMap</a>, a value-based dictionary (associative array). +</ul> +<p> The pointer-based collections are: +<ul> +<li> <a href="qcache.html">QCache</a> and <a href="qintcache.html">QIntCache</a>, LRU (least recently used) caches. +<li> <a href="qdict.html">QDict</a>, <a href="qintdict.html">QIntDict</a> and <a href="qptrdict.html">QPtrDict</a> dictionaries. +<li> <a href="qptrlist.html">QPtrList</a>, a doubly linked list. +<li> <a href="qptrqueue.html">QPtrQueue</a>, a FIFO (first in, first out) queue. +<li> <a href="qptrstack.html">QPtrStack</a>, a LIFO (last in, first out) stack. +<li> <a href="qptrvector.html">QPtrVector</a>, a vector. +</ul> +<p> <a href="qmemarray.html">QMemArray</a> is exceptional; it is neither pointer nor value based, +but memory based. For maximum efficiency with the simple data types +usually used in arrays, it uses bitwise operations to copy and compare +array elements. +<p> Some of these classes have corresponding iterators. An iterator +is a class for traversing the items in a collection: +<ul> +<li> <a href="qcacheiterator.html">QCacheIterator</a> and +<a href="qintcacheiterator.html">QIntCacheIterator</a> +<li> <a href="qdictiterator.html">QDictIterator</a>, +<a href="qintdictiterator.html">QIntDictIterator</a>, and +<a href="qptrdictiterator.html">QPtrDictIterator</a> +<li> <a href="qptrlistiterator.html">QPtrListIterator</a> +<li> <a href="qvaluelistiterator.html">QValueListIterator</a>, and +<a href="qvaluelistconstiterator.html">QValueListConstIterator</a> +<li> <a href="qmapiterator.html">QMapIterator</a>, and +<a href="qmapconstiterator.html">QMapConstIterator</a> +</ul> +<p> The value-based collections plus algorithms operating on them are +grouped together in the <a href="qt-template-lib.html">Qt Template +Library</a>; see also the <a href="qtl.html">Qt Template +Library Classes</a>. +<p> The rest of this page dicusses the pointer-based containers. +<p> <h2> Architecture of the pointer-based containers +</h2> +<a name="1"></a><p> There are four internal base classes for the pointer-based +containers (QGCache, QGDict, QGList and QGVector) that operate on +void pointers. A thin template layer implements the actual +collections by casting item pointers to and from void pointers. +<p> This strategy allows Qt's templates to be very economical on space +(instantiating one of these templates adds only inlinable calls to +the base classes), without hurting performance. +<p> <h2> A <a href="qptrlist.html">QPtrList</a> Example +</h2> +<a name="2"></a><p> This example shows how to store Employee items in a list and prints +them out in reverse order: +<p> <pre> + #include <<a href="qptrlist-h.html">qptrlist.h</a>> + #include <<a href="qstring-h.html">qstring.h</a>> + #include <stdio.h> + + class Employee + { + public: + Employee( const char *name, int salary ) { n=name; s=salary; } + const char *name() const { return n; } + int salary() const { return s; } + private: + <a href="qstring.html">QString</a> n; + int s; + }; + + int main() + { + <a href="qptrlist.html">QPtrList</a><Employee> list; // list of pointers to Employee + list.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>( TRUE ); // delete items when they are removed + + list.<a href="qptrlist.html#append">append</a>( new Employee("Bill", 50000) ); + list.<a href="qptrlist.html#append">append</a>( new Employee("Steve",80000) ); + list.<a href="qptrlist.html#append">append</a>( new Employee("Ron", 60000) ); + + <a href="qptrlistiterator.html">QPtrListIterator</a><Employee> it(list); // iterator for employee list + for ( it.<a href="qptrlistiterator.html#toLast">toLast</a>(); it.<a href="qptrlistiterator.html#current">current</a>(); --it) ) { + Employee *emp = it.<a href="qptrlistiterator.html#current">current</a>(); + printf( "%s earns %d\n", emp->name(), emp->salary() ); + } + + return 0; + } +</pre> + +<p> Program output: +<pre> + Ron earns 60000 + Steve earns 80000 + Bill earns 50000 +</pre> + +<p> <h2> Managing Collection Items +</h2> +<a name="3"></a><p> All pointer-based collections inherit the <a href="qptrcollection.html">QPtrCollection</a> base class. +This class only knows about the number of items in the collection and +the deletion strategy. +<p> By default, items in a collection are not deleted when they are +removed from the collection. The <a href="qptrcollection.html#setAutoDelete">QPtrCollection::setAutoDelete</a>() +function specifies the deletion strategy. In the list example, we +enable auto-deletion to make the list delete the items when they are +removed from the list. +<p> When inserting an item into a collection, only the pointer is copied, +not the item itself. This is called a <a href="shclass.html#shallow-copy">shallow copy</a>. It is possible to +make the collection copy all of the item's data (known as a <a href="shclass.html#deep-copy">deep copy</a>) +when an item is inserted. All collection functions that insert an +item call the virtual function <a href="qptrcollection.html#newItem">QPtrCollection::newItem</a>() for the item +to be inserted. Inherit a collection and reimplement it if you want +to have deep copies in your collection. +<p> When removing an item from a list, the virtual function +<a href="qptrcollection.html#deleteItem">QPtrCollection::deleteItem</a>() is called. The default implementation +in all collection classes deletes the item if auto-deletion is +enabled. +<p> <h2> Usage +</h2> +<a name="4"></a><p> A pointer-based collection class, such as <a href="qptrlist.html">QPtrList</a><type>, defines a +collection of <em>pointers</em> to <em>type</em> objects. The pointer (*) is +implicit. +<p> We discuss <a href="qptrlist.html">QPtrList</a> here, but the same techniques apply to all +pointer-based collection classes and all collection class iterators. +<p> Template instantiation: +<pre> + <a href="qptrlist.html">QPtrList</a><Employee> list; // wherever the list is used +</pre> + +<p> The item's class or type, Employee in our example, must be defined prior +to the list definition. +<p> <pre> + // Does not work: Employee is not defined + class Employee; + <a href="qptrlist.html">QPtrList</a><Employee> list; + + // This works: Employee is defined before it is used + class Employee { + ... + }; + <a href="qptrlist.html">QPtrList</a><Employee> list; +</pre> + +<p> <h2> Iterators +</h2> +<a name="5"></a><p> Although <a href="qptrlist.html">QPtrList</a> has member functions to traverse the list, it can +often be better to make use of an iterator. <a href="qptrlistiterator.html">QPtrListIterator</a> is very +safe and can traverse lists that are being modified at the same time. +Multiple iterators can work independently on the same collection. +<p> A <a href="qptrlist.html">QPtrList</a> has an internal list of all the iterators that are +currently operating on it. When a list entry is removed, the list +updates all iterators accordingly. +<p> The <a href="qdict.html">QDict</a> and <a href="qcache.html">QCache</a> collections have no traversal functions. To +traverse these collections, you must use <a href="qdictiterator.html">QDictIterator</a> or <a href="qcacheiterator.html">QCacheIterator</a>. +<p> <h2> Predefined Collections +</h2> +<a name="6"></a><p> Qt has the following predefined collection classes: +<ul> +<li> String lists: <a href="qstrlist.html">QStrList</a>, <a href="qstrilist.html">QStrIList</a> (<a href="qstrlist-h.html">qstrlist.h</a>) and +<a href="qstringlist.html">QStringList</a> (<a href="qstringlist-h.html">qstringlist.h</a>) +<li> String vectors: QStrVec and QStrIVec (qstrvec.h); these are obsolete +</ul> +<p> In almost all cases you would choose <a href="qstringlist.html">QStringList</a>, a value +list of <a href="shclass.html#implicitly-shared">implicitly shared</a> <a href="qstring.html">QString</a> Unicode strings. QPtrStrList and +QPtrStrIList store only char pointers, not the strings themselves. +<p> <h2> List of Pointer-based Collection Classes and Related +Iterator Classes +</h2> +<a name="7"></a><p> +<p><table width="100%"> +<tr bgcolor=#f0f0f0><td><b><a href="qasciicache.html">QAsciiCache</a></b><td>Template class that provides a cache based on char* keys +<tr bgcolor=#f0f0f0><td><b><a href="qasciicacheiterator.html">QAsciiCacheIterator</a></b><td>Iterator for QAsciiCache collections +<tr bgcolor=#f0f0f0><td><b><a href="qasciidict.html">QAsciiDict</a></b><td>Template class that provides a dictionary based on char* keys +<tr bgcolor=#f0f0f0><td><b><a href="qasciidictiterator.html">QAsciiDictIterator</a></b><td>Iterator for QAsciiDict collections +<tr bgcolor=#f0f0f0><td><b><a href="qbitarray.html">QBitArray</a></b><td>Array of bits +<tr bgcolor=#f0f0f0><td><b><a href="qbitval.html">QBitVal</a></b><td>Internal class, used with QBitArray +<tr bgcolor=#f0f0f0><td><b><a href="qbuffer.html">QBuffer</a></b><td>I/O device that operates on a QByteArray +<tr bgcolor=#f0f0f0><td><b><a href="qbytearray.html">QByteArray</a></b><td>Array of bytes +<tr bgcolor=#f0f0f0><td><b><a href="qcache.html">QCache</a></b><td>Template class that provides a cache based on QString keys +<tr bgcolor=#f0f0f0><td><b><a href="qcacheiterator.html">QCacheIterator</a></b><td>Iterator for QCache collections +<tr bgcolor=#f0f0f0><td><b><a href="qcstring.html">QCString</a></b><td>Abstraction of the classic C zero-terminated char array (char *) +<tr bgcolor=#f0f0f0><td><b><a href="qdict.html">QDict</a></b><td>Template class that provides a dictionary based on QString keys +<tr bgcolor=#f0f0f0><td><b><a href="qdictiterator.html">QDictIterator</a></b><td>Iterator for QDict collections +<tr bgcolor=#f0f0f0><td><b><a href="qintcache.html">QIntCache</a></b><td>Template class that provides a cache based on long keys +<tr bgcolor=#f0f0f0><td><b><a href="qintcacheiterator.html">QIntCacheIterator</a></b><td>Iterator for QIntCache collections +<tr bgcolor=#f0f0f0><td><b><a href="qintdict.html">QIntDict</a></b><td>Template class that provides a dictionary based on long keys +<tr bgcolor=#f0f0f0><td><b><a href="qintdictiterator.html">QIntDictIterator</a></b><td>Iterator for QIntDict collections +<tr bgcolor=#f0f0f0><td><b><a href="qobjectlist.html">QObjectList</a></b><td>QPtrList of QObjects +<tr bgcolor=#f0f0f0><td><b><a href="qobjectlistiterator.html">QObjectListIterator</a></b><td>Iterator for QObjectLists +<tr bgcolor=#f0f0f0><td><b><a href="qptrcollection.html">QPtrCollection</a></b><td>The base class of most pointer-based Qt collections +<tr bgcolor=#f0f0f0><td><b><a href="qptrdict.html">QPtrDict</a></b><td>Template class that provides a dictionary based on void* keys +<tr bgcolor=#f0f0f0><td><b><a href="qptrdictiterator.html">QPtrDictIterator</a></b><td>Iterator for QPtrDict collections +<tr bgcolor=#f0f0f0><td><b><a href="qptrlist.html">QPtrList</a></b><td>Template class that provides a list +<tr bgcolor=#f0f0f0><td><b><a href="qptrlistiterator.html">QPtrListIterator</a></b><td>Iterator for QPtrList collections +<tr bgcolor=#f0f0f0><td><b><a href="qptrqueue.html">QPtrQueue</a></b><td>Template class that provides a queue +<tr bgcolor=#f0f0f0><td><b><a href="qstrilist.html">QStrIList</a></b><td>Doubly-linked list of char* with case-insensitive comparison +<tr bgcolor=#f0f0f0><td><b><a href="qstrlist.html">QStrList</a></b><td>Doubly-linked list of char* +</table> +<!-- eof --> +<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> |