source: trunk/doc/src/frameworks-technologies/containers.qdoc@ 846

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/*!
    \group tools
    \title Non-GUI Classes
    \ingroup groups

    \brief Collection classes such as list, queue, stack and string, along
    with other classes that can be used without needing QApplication.

    The non-GUI classes are general-purpose collection and string classes
    that may be used independently of the GUI classes.

    In particular, these classes do not depend on QApplication at all,
    and so can be used in non-GUI programs.

*/

/*!
    \page containers.html
    \title Container Classes
    \ingroup technology-apis
    \ingroup groups
    \ingroup qt-basic-concepts
    \keyword container class
    \keyword container classes

    \brief Qt's template-based container classes.

    \tableofcontents

    \section1 Introduction

    The Qt library provides a set of general purpose template-based
    container classes. These classes can be used to store items of a
    specified type. For example, if you need a resizable array of
    \l{QString}s, use QVector<QString>.

    These container classes are designed to be lighter, safer, and
    easier to use than the STL containers. If you are unfamiliar with
    the STL, or prefer to do things the "Qt way", you can use these
    classes instead of the STL classes.

    The container classes are \l{implicitly shared}, they are
    \l{reentrant}, and they are optimized for speed, low memory
    consumption, and minimal inline code expansion, resulting in
    smaller executables. In addition, they are \l{thread-safe}
    in situations where they are used as read-only containers
    by all threads used to access them.

    For traversing the items stored in a container, you can use one
    of two types of iterators: \l{Java-style iterators} and
    \l{STL-style iterators}. The Java-style iterators are easier to
    use and provide high-level functionality, whereas the STL-style
    iterators are slightly more efficient and can be used together
    with Qt's and STL's \l{generic algorithms}.

    Qt also offers a \l{foreach} keyword that make it very
    easy to iterate over all the items stored in a container.

    \section1 The Container Classes

    Qt provides the following sequential containers: QList,
    QLinkedList, QVector, QStack, and QQueue. For most
    applications, QList is the best type to use. Although it is
    implemented as an array-list, it provides very fast prepends and
    appends. If you really need a linked-list, use QLinkedList; if you
    want your items to occupy consecutive memory locations, use QVector.
    QStack and QQueue are convenience classes that provide LIFO and
    FIFO semantics.

    Qt also provides these associative containers: QMap,
    QMultiMap, QHash, QMultiHash, and QSet. The "Multi" containers
    conveniently support multiple values associated with a single
    key. The "Hash" containers provide faster lookup by using a hash
    function instead of a binary search on a sorted set.

    As special cases, the QCache and QContiguousCache classes provide
    efficient hash-lookup of objects in a limited cache storage.

    \table
    \header \o Class \o Summary

    \row \o \l{QList}<T>
    \o This is by far the most commonly used container class. It
    stores a list of values of a given type (T) that can be accessed
    by index. Internally, the QList is implemented using an array,
    ensuring that index-based access is very fast.

    Items can be added at either end of the list using
    QList::append() and QList::prepend(), or they can be inserted in
    the middle using QList::insert(). More than any other container
    class, QList is highly optimized to expand to as little code as
    possible in the executable. QStringList inherits from
    QList<QString>.

    \row \o \l{QLinkedList}<T>
    \o This is similar to QList, except that it uses