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Please review the following information to ensure ** the GNU Free Documentation License version 1.3 requirements ** will be met: https://www.gnu.org/licenses/fdl-1.3.html. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \headerfile \title Generic Algorithms \ingroup funclists \keyword generic algorithms \brief The header includes the generic, template-based algorithms. Qt provides a number of global template functions in \c that work on containers and perform small tasks to make life easier, such as qDeleteAll(), which invokes \c{operator delete} on all items in a given container or in a given range. You can use these algorithms with any \l {container class} that provides STL-style iterators, including Qt's QList, QMap, and QHash classes. Most algorithms take \l {STL-style iterators} as parameters. The algorithms are generic in the sense that they aren't bound to a specific iterator class; you can use them with any iterators that meet a certain set of requirements. Different algorithms can have different requirements for the iterators they accept. The iterator types required are specified for each algorithm. If an iterator of the wrong type is passed (for example, if QList::ConstIterator is passed as an \l {Output Iterators}{output iterator}), you will always get a compiler error, although not necessarily a very informative one. Some algorithms have special requirements on the value type stored in the containers. For example, qDeleteAll() requires that the value type is a non-const pointer type (for example, QWidget *). The value type requirements are specified for each algorithm, and the compiler will produce an error if a requirement isn't met. The generic algorithms can be used on other container classes than those provided by Qt and STL. The syntax of STL-style iterators is modeled after C++ pointers, so it's possible to use plain arrays as containers and plain pointers as iterators. \section1 Types of Iterators The algorithms have certain requirements on the iterator types they accept, and these are specified individually for each function. The compiler will produce an error if a requirement isn't met. \section2 Input Iterators An \e{input iterator} is an iterator that can be used for reading data sequentially from a container. It must provide the following operators: \c{==} and \c{!=} for comparing two iterators, unary \c{*} for retrieving the value stored in the item, and prefix \c{++} for advancing to the next item. The Qt containers' iterator types (const and non-const) are all input iterators. \section2 Output Iterators An output iterator is an iterator that can be used for writing data sequentially to a container or to some output stream. It must provide the following operators: unary \c{*} for writing a value (i.e., \c{*it = val}) and prefix \c{++} for advancing to the next item. The Qt containers' non-const iterator types are all output iterators. \section2 Forward Iterators A \e{forward iterator} is an iterator that meets the requirements of both input iterators and output iterators. The Qt containers' non-const iterator types are all forward iterators. \section2 Bidirectional Iterators A \e{bidirectional iterator} is an iterator that meets the requirements of forward iterators but that in addition supports prefix \c{--} for iterating backward. The Qt containers' non-const iterator types are all bidirectional iterators. \section2 Random Access Iterators The last category, \e{random access iterators}, is the most powerful type of iterator. It supports all the requirements of a bidirectional iterator, and supports the following operations: \table \row \li \c{i += n} \li advances iterator \c i by \c n positions \row \li \c{i -= n} \li moves iterator \c i back by \c n positions \row \li \c{i + n} or \c{n + i} \li returns the iterator for the item \c n positions ahead of iterator \c i \row \li \c{i - n} \li returns the iterator for the item \c n positions behind of iterator \c i \row \li \c{i - j} \li returns the number of items between iterators \c i and \c j \row \li \c{i[n]} \li same as \c{*(i + n)} \row \li \c{i < j} \li returns \c true if iterator \c j comes after iterator \c i \endtable QList's non-const iterator type is random access iterator. \sa {container classes}, */ /*! \fn template void qSwap(T &var1, T &var2) \relates \deprecated Use \c std::swap instead. Exchanges the values of variables \a var1 and \a var2. Example: \snippet code/doc_src_qalgorithms.cpp 0 */ /*! \fn template void qDeleteAll(ForwardIterator begin, ForwardIterator end) \relates Deletes all the items in the range [\a begin, \a end) using the C++ \c delete operator. The item type must be a pointer type (for example, \c{QWidget *}). Example: \snippet code/doc_src_qalgorithms.cpp 1 Notice that qDeleteAll() doesn't remove the items from the container; it merely calls \c delete on them. In the example above, we call clear() on the container to remove the items. This function can also be used to delete items stored in associative containers, such as QMap and QHash. Only the objects stored in each container will be deleted by this function; objects used as keys will not be deleted. \sa {forward iterators} */ /*! \fn template void qDeleteAll(const Container &c) \relates \overload This is the same as qDeleteAll(\a{c}.begin(), \a{c}.end()). */ /*! \fn uint qPopulationCount(quint8 v) \relates \since 5.2 Returns the number of bits set in \a v. This number is also called the Hamming Weight of \a v. */ /*! \fn uint qPopulationCount(quint16 v) \relates \since 5.2 \overload */ /*! \fn uint qPopulationCount(quint32 v) \relates \since 5.2 \overload */ /*! \fn uint qPopulationCount(quint64 v) \relates \since 5.2 \overload */ /*! \fn uint qCountTrailingZeroBits(quint8 v) \relates \since 5.6 Returns the number of consecutive zero bits in \a v, when searching from the LSB. For example, qCountTrailingZeroBits(1) returns 0 and qCountTrailingZeroBits(8) returns 3. */ /*! \fn uint qCountTrailingZeroBits(quint16 v) \relates \since 5.6 \overload */ /*! \fn uint qCountTrailingZeroBits(quint32 v) \relates \since 5.6 \overload */ /*! \fn uint qCountTrailingZeroBits(quint64 v) \relates \since 5.6 \overload */ /*! \fn uint qCountLeadingZeroBits(quint8 v) \relates \since 5.6 Returns the number of consecutive zero bits in \a v, when searching from the MSB. For example, qCountLeadingZeroBits(quint8(1)) returns 7 and qCountLeadingZeroBits(quint8(8)) returns 4. */ /*! \fn uint qCountLeadingZeroBits(quint16 v) \relates \since 5.6 Returns the number of consecutive zero bits in \a v, when searching from the MSB. For example, qCountLeadingZeroBits(quint16(1)) returns 15 and qCountLeadingZeroBits(quint16(8)) returns 12. */ /*! \fn uint qCountLeadingZeroBits(quint32 v) \relates \since 5.6 Returns the number of consecutive zero bits in \a v, when searching from the MSB. For example, qCountLeadingZeroBits(quint32(1)) returns 31 and qCountLeadingZeroBits(quint32(8)) returns 28. */ /*! \fn uint qCountLeadingZeroBits(quint64 v) \relates \since 5.6 Returns the number of consecutive zero bits in \a v, when searching from the MSB. For example, qCountLeadingZeroBits(quint64(1)) returns 63 and qCountLeadingZeroBits(quint64(8)) returns 60. */