You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
251 lines
14 KiB
251 lines
14 KiB
<!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> TQt 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">TQt Template Library</a> documentation for
|
|
details.
|
|
<p> The value-based collections are:
|
|
<ul>
|
|
<li> <a href="ntqvaluelist.html">TQValueList</a>, a value-based list.
|
|
<li> <a href="ntqvaluevector.html">TQValueVector</a>, a value-based vector.
|
|
<li> <a href="ntqvaluestack.html">TQValueStack</a>, a value-based stack.
|
|
<li> <a href="ntqmap.html">TQMap</a>, a value-based dictionary (associative array).
|
|
</ul>
|
|
<p> The pointer-based collections are:
|
|
<ul>
|
|
<li> <a href="ntqcache.html">TQCache</a> and <a href="ntqintcache.html">TQIntCache</a>, LRU (least recently used) caches.
|
|
<li> <a href="ntqdict.html">TQDict</a>, <a href="ntqintdict.html">TQIntDict</a> and <a href="ntqptrdict.html">TQPtrDict</a> dictionaries.
|
|
<li> <a href="ntqptrlist.html">TQPtrList</a>, a doubly linked list.
|
|
<li> <a href="ntqptrqueue.html">TQPtrQueue</a>, a FIFO (first in, first out) queue.
|
|
<li> <a href="ntqptrstack.html">TQPtrStack</a>, a LIFO (last in, first out) stack.
|
|
<li> <a href="ntqptrvector.html">TQPtrVector</a>, a vector.
|
|
</ul>
|
|
<p> <a href="ntqmemarray.html">TQMemArray</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">TQCacheIterator</a> and
|
|
<a href="qintcacheiterator.html">TQIntCacheIterator</a>
|
|
<li> <a href="qdictiterator.html">TQDictIterator</a>,
|
|
<a href="qintdictiterator.html">TQIntDictIterator</a>, and
|
|
<a href="qptrdictiterator.html">TQPtrDictIterator</a>
|
|
<li> <a href="qptrlistiterator.html">TQPtrListIterator</a>
|
|
<li> <a href="qvaluelistiterator.html">TQValueListIterator</a>, and
|
|
<a href="qvaluelistconstiterator.html">TQValueListConstIterator</a>
|
|
<li> <a href="qmapiterator.html">TQMapIterator</a>, and
|
|
<a href="qmapconstiterator.html">TQMapConstIterator</a>
|
|
</ul>
|
|
<p> The value-based collections plus algorithms operating on them are
|
|
grouped together in the <a href="qt-template-lib.html">TQt Template
|
|
Library</a>; see also the <a href="ntqtl.html">TQt 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 (TQGCache, TQGDict, TQGList and TQGVector) 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 TQt'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="ntqptrlist.html">TQPtrList</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">ntqptrlist.h</a>>
|
|
#include <<a href="qstring-h.html">ntqstring.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="ntqstring.html">TQString</a> n;
|
|
int s;
|
|
};
|
|
|
|
int main()
|
|
{
|
|
<a href="ntqptrlist.html">TQPtrList</a><Employee> list; // list of pointers to Employee
|
|
list.<a href="ntqptrcollection.html#setAutoDelete">setAutoDelete</a>( TRUE ); // delete items when they are removed
|
|
|
|
list.<a href="ntqptrlist.html#append">append</a>( new Employee("Bill", 50000) );
|
|
list.<a href="ntqptrlist.html#append">append</a>( new Employee("Steve",80000) );
|
|
list.<a href="ntqptrlist.html#append">append</a>( new Employee("Ron", 60000) );
|
|
|
|
<a href="qptrlistiterator.html">TQPtrListIterator</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="ntqptrcollection.html">TQPtrCollection</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="ntqptrcollection.html#setAutoDelete">TQPtrCollection::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="ntqptrcollection.html#newItem">TQPtrCollection::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="ntqptrcollection.html#deleteItem">TQPtrCollection::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="ntqptrlist.html">TQPtrList</a><type>, defines a
|
|
collection of <em>pointers</em> to <em>type</em> objects. The pointer (*) is
|
|
implicit.
|
|
<p> We discuss <a href="ntqptrlist.html">TQPtrList</a> here, but the same techniques apply to all
|
|
pointer-based collection classes and all collection class iterators.
|
|
<p> Template instantiation:
|
|
<pre>
|
|
<a href="ntqptrlist.html">TQPtrList</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="ntqptrlist.html">TQPtrList</a><Employee> list;
|
|
|
|
// This works: Employee is defined before it is used
|
|
class Employee {
|
|
...
|
|
};
|
|
<a href="ntqptrlist.html">TQPtrList</a><Employee> list;
|
|
</pre>
|
|
|
|
<p> <h2> Iterators
|
|
</h2>
|
|
<a name="5"></a><p> Although <a href="ntqptrlist.html">TQPtrList</a> has member functions to traverse the list, it can
|
|
often be better to make use of an iterator. <a href="qptrlistiterator.html">TQPtrListIterator</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="ntqptrlist.html">TQPtrList</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="ntqdict.html">TQDict</a> and <a href="ntqcache.html">TQCache</a> collections have no traversal functions. To
|
|
traverse these collections, you must use <a href="qdictiterator.html">TQDictIterator</a> or <a href="qcacheiterator.html">TQCacheIterator</a>.
|
|
<p> <h2> Predefined Collections
|
|
</h2>
|
|
<a name="6"></a><p> TQt has the following predefined collection classes:
|
|
<ul>
|
|
<li> String lists: <a href="ntqstrlist.html">TQStrList</a>, <a href="qstrilist.html">TQStrIList</a> (<a href="qstrlist-h.html">ntqstrlist.h</a>) and
|
|
<a href="ntqstringlist.html">TQStringList</a> (<a href="qstringlist-h.html">ntqstringlist.h</a>)
|
|
<li> String vectors: TQStrVec and TQStrIVec (ntqstrvec.h); these are obsolete
|
|
</ul>
|
|
<p> In almost all cases you would choose <a href="ntqstringlist.html">TQStringList</a>, a value
|
|
list of <a href="shclass.html#implicitly-shared">implicitly shared</a> <a href="ntqstring.html">TQString</a> Unicode strings. TQPtrStrList and
|
|
TQPtrStrIList 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="ntqasciicache.html">TQAsciiCache</a></b><td>Template class that provides a cache based on char* keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qasciicacheiterator.html">TQAsciiCacheIterator</a></b><td>Iterator for TQAsciiCache collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqasciidict.html">TQAsciiDict</a></b><td>Template class that provides a dictionary based on char* keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qasciidictiterator.html">TQAsciiDictIterator</a></b><td>Iterator for TQAsciiDict collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqbitarray.html">TQBitArray</a></b><td>Array of bits
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qbitval.html">TQBitVal</a></b><td>Internal class, used with TQBitArray
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqbuffer.html">TQBuffer</a></b><td>I/O device that operates on a TQByteArray
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qbytearray.html">TQByteArray</a></b><td>Array of bytes
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqcache.html">TQCache</a></b><td>Template class that provides a cache based on TQString keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qcacheiterator.html">TQCacheIterator</a></b><td>Iterator for TQCache collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqcstring.html">TQCString</a></b><td>Abstraction of the classic C zero-terminated char array (char *)
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqdict.html">TQDict</a></b><td>Template class that provides a dictionary based on TQString keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qdictiterator.html">TQDictIterator</a></b><td>Iterator for TQDict collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqintcache.html">TQIntCache</a></b><td>Template class that provides a cache based on long keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qintcacheiterator.html">TQIntCacheIterator</a></b><td>Iterator for TQIntCache collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqintdict.html">TQIntDict</a></b><td>Template class that provides a dictionary based on long keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qintdictiterator.html">TQIntDictIterator</a></b><td>Iterator for TQIntDict collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="tqobjectlist.html">TQObjectList</a></b><td>TQPtrList of TQObjects
|
|
<tr bgcolor=#f0f0f0><td><b><a href="tqobjectlistiterator.html">TQObjectListIterator</a></b><td>Iterator for TQObjectLists
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqptrcollection.html">TQPtrCollection</a></b><td>The base class of most pointer-based TQt collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqptrdict.html">TQPtrDict</a></b><td>Template class that provides a dictionary based on void* keys
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qptrdictiterator.html">TQPtrDictIterator</a></b><td>Iterator for TQPtrDict collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqptrlist.html">TQPtrList</a></b><td>Template class that provides a list
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qptrlistiterator.html">TQPtrListIterator</a></b><td>Iterator for TQPtrList collections
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqptrqueue.html">TQPtrQueue</a></b><td>Template class that provides a queue
|
|
<tr bgcolor=#f0f0f0><td><b><a href="qstrilist.html">TQStrIList</a></b><td>Doubly-linked list of char* with case-insensitive comparison
|
|
<tr bgcolor=#f0f0f0><td><b><a href="ntqstrlist.html">TQStrList</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>TQt 3.3.8</div>
|
|
</table></div></address></body>
|
|
</html>
|