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RedHat 9 (Linux i386) - man page for qvaluevector (redhat section 3qt)

QValueVector(3qt)								QValueVector(3qt)

NAME
       QValueVector - Value-based template class that provides a dynamic array

SYNOPSIS
       All the functions in this class are reentrant when Qt is built with thread support.</p>

       #include <qvaluevector.h>

   Public Members
       typedef T value_type
       typedef value_type * pointer
       typedef const value_type * const_pointer
       typedef value_type * iterator
       typedef const value_type * const_iterator
       typedef value_type & reference
       typedef const value_type & const_reference
       typedef size_t size_type
       typedef ptrdiff_t difference_type
       QValueVector ()
       QValueVector ( const QValueVector<T> & v )
       QValueVector ( size_type n, const T & val = T ( ) )
       QValueVector ( std::vector<T> & v )
       QValueVector ( const std::vector<T> & v )
       ~QValueVector ()
       QValueVector<T> & operator= ( const QValueVector<T> & v )
       QValueVector<T> & operator= ( const std::vector<T> & v )
       size_type size () const
       bool empty () const
       size_type capacity () const
       iterator begin ()
       const_iterator begin () const
       iterator end ()
       const_iterator end () const
       reference at ( size_type i, bool * ok = 0 )
       const_reference at ( size_type i, bool * ok = 0 ) const
       reference operator[] ( size_type i )
       const_reference operator[] ( size_type i ) const
       reference front ()
       const_reference front () const
       reference back ()
       const_reference back () const
       void push_back ( const T & x )
       void pop_back ()
       iterator insert ( iterator pos, const T & x )
       iterator insert ( iterator pos, size_type n, const T & x )
       void reserve ( size_type n )
       void resize ( size_type n, const T & val = T ( ) )
       void clear ()
       iterator erase ( iterator pos )
       iterator erase ( iterator first, iterator last )
       bool operator== ( const QValueVector<T> & x )
       bool operator== ( const QValueVector<T> & x ) const
       typedef T ValueType
       typedef ValueType * Iterator
       typedef const ValueType * ConstIterator
       size_type count () const
       bool isEmpty () const
       reference first ()
       const_reference first () const
       reference last ()
       const_reference last () const
       void append ( const T & x )

DESCRIPTION
       The QValueVector class is a value-based template class that provides a dynamic array.

       QValueVector is a Qt implementation of an STL-like vector container. It can be used in
       your application if the standard vector is not available for your target platforms.
       QValueVector is part of the Qt Template Library.

       QValueVector<T> defines a template instance to create a vector of values that all have the
       class T. QValueVector does not store pointers to the members of the vector; it holds a
       copy of every member. QValueVector is said to be value based; in contrast, QPtrList and
       QDict are pointer based.

       QValueVector contains and manages a collection of objects of type T and provides random
       access iterators that allow the contained objects to be addressed. QValueVector owns the
       contained elements. For more relaxed ownership semantics, see QPtrCollection and friends,
       which are pointer-based containers.

       QValueVector provides good performance if you append or remove elements from the end of
       the vector. If you insert or remove elements from anywhere but the end, performance is
       very bad. The reason for this is that elements must to be copied into new positions.

       Some classes cannot be used within a QValueVector: for example, all classes derived from
       QObject and thus all classes that implement widgets. Only values can be used in a
       QValueVector. To qualify as a value the class must provide:

       a copy constructor;

       an assignment operator;

       a default constructor, i.e., a constructor that does not take any arguments.

       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.

       QValueVector uses an STL-like syntax to manipulate and address the objects it contains.
       See this document for more information.

       Example:

	   #include <qvaluevector.h>
	   #include <qstring.h>
	   #include <stdio.h>
	   class Employee
	   {
	   public:
	       Employee(): s(0) {}
	       Employee( const QString& name, int salary )
		   : n( name ), s( salary )
	       { }
	       QString name() const { return n; }
	       int salary() const { return s; }
	       void setSalary( int salary ) { s = salary; }
	       QString name()	const	       { return n; }
	       int     salary() const	       { return s; }
	       void    setSalary( int salary ) { s = salary; }
	   private:
	       QString n;
	       int     s;
	   };
	   int main()
	   {
	       typedef QValueVector<Employee> EmployeeVector;
	       EmployeeVector vec( 3 );  // vector of 3 Employees
	       vec[0] = Employee( "Bill", 50000 );
	       vec[1] = Employee( "Steve", 80000 );
	       vec[2] = Employee( "Ron", 60000 );
	       Employee joe( "Joe", 50000 );
	       vec.push_back( joe );  // vector expands to accommodate 4 Employees
	       joe.setSalary( 70000 );
	       EmployeeVector::iterator it;
	       for( it = vec.begin(); it != vec.end(); ++it )
		   printf( "%s earns %d\n", (*it).name().latin1(), (*it).salary() );
	       return 0;
	   }

       Program output:

	       Bill earns 50000
	       Steve earns 80000
	       Ron earns 60000
	       Joe earns 50000

       As you can see, the most recent change to Joe's salary did not affect the value in the
       vector because the vector created a copy of Joe's entry.

       Many Qt functions return const value vectors; to iterate over these you should make a copy
       and iterate over the copy.

       There are several ways to find items in the vector. The begin() and end() functions return
       iterators to the beginning and end of the vector. The advantage of getting an iterator is
       that you can move forward or backward from this position 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 vector it
       belongs to, however it is not dereferenceable; operator*() will not return a well-defined
       value. If the vector is empty(), the iterator returned by begin() will equal the iterator
       returned by end().

       The fastest way to access an element of a vector is by using operator[]. This function
       provides random access and will return a reference to the element located at the specified
       index. Thus, you can access every element directly, in constant time, providing you know
       the location of the element. It is undefined to access an element that does not exist
       (your application will probably crash). For example:

	   QValueVector<int> vec1;  // an empty vector
	   vec1[10] = 4;  // WARNING: undefined, probably a crash
	   QValueVector<QString> vec2(25); // initialize with 25 elements
	   vec2[10] = "Dave";  // OK

       Whenever inserting, removing or referencing elements in a vector, always make sure you are
       referring to valid positions. For example:

	   void func( QValueVector<int>& vec )
	   {
	       if ( vec.size() > 10 ) {
		   vec[9] = 99; // OK
	       }
	   };

       The iterators provided by vector are random access iterators, therefore you can use them
       with many generic algorithms, for example, algorithms provided by the STL or the QTL.

       Another way to find an element in the vector is by using the std::find() or qFind()
       algorithms. For example:

	   QValueVector<int> vec;
	   ...
	   QValueVector<int>::const_iterator it = qFind( vec.begin(), vec.end(), 3 );
	   if ( it != vector.end() )
	       // 'it' points to the found element

       It is safe to have multiple iterators on the vector at the same time. Since QValueVector
       manages memory dynamically, all iterators can become invalid if a memory reallocation
       occurs. For example, if some member of the vector is removed, iterators that point to the
       removed element and to all following elements become invalidated. Inserting into the
       middle of the vector will invalidate all iterators. For convenience, the function back()
       returns a reference to the last element in the vector, and front() returns a reference to
       the first element. If the vector is empty(), both back() and front() have undefined
       behavior (your application will crash or do unpredictable things). Use back() and front()
       with caution, for example:

	   QValueVector<int> vec( 3 );
	   vec.push_back( 1 );
	   vec.push_back( 2 );
	   vec.push_back( 3 );
	   ...
	   if ( !vec.empty() ) {
	       // OK: modify the first element
	       int& i = vec.front();
	       i = 18;
	   }
	   ...
	   QValueVector<double> dvec;
	   double d = dvec.back(); // undefined behavior

       Because QValueVector manages memory dynamically, it is recommended that you contruct a
       vector with an initial size. Inserting and removing elements happens fastest when:

       Inserting or removing elements happens at the end() of the vector;

       The vector does not need to allocate additional memory.

       By creating a QValueVector with a sufficiently large initial size, there will be less
       memory allocations. Do not use an initial size that is too big, since it will still take
       time to construct all the empty entries, and the extra space will be wasted if it is never
       used.

       Because QValueVector is value-based there is no need to be careful about deleting elements
       in the vector. The vector holds its own copies and will free them if the corresponding
       member or the vector itself is deleted. You can force the vector to free all of its items
       with clear().

       QValueVector is shared implicitly, which means it can be copied in constant time. If
       multiple QValueVector instances share the same data and one needs to modify its contents,
       this modifying instance makes a copy and modifies its private copy; it thus does not
       affect the other instances. This is often called "copy on write". If a QValueVector is
       being used in a multi-threaded program, you must protect all access to the vector. See
       QMutex.

       There are several ways to insert elements into the vector. The push_back() function insert
       elements into the end of the vector, and is usually fastest. The insert() function can be
       used to add elements at specific positions within the vector.

       Items can be also be removed from the vector in several ways. There are several variants
       of the erase() function which removes a specific element, or range of elements, from the
       vector.

       Vectors can be also sorted with various STL algorithms , or it can be sorted using the Qt
       Template Library. For example with qHeapSort():

       Example:

	   QValueVector<int> v( 4 );
	   v.push_back( 5 );
	   v.push_back( 8 );
	   v.push_back( 3 );
	   v.push_back( 4 );
	   qHeapSort( v );

       QValueVector stores its elements in contiguous memory. This means that you can use a
       QValueVector in any situation that requires an array.

       See also Qt Template Library Classes, Implicitly and Explicitly Shared Classes, and Non-
       GUI Classes.

   Member Type Documentation
QValueVector::ConstIterator
       The vector's const iterator type.

QValueVector::Iterator
       The vector's iterator type.

QValueVector::ValueType
       The type of the object stored in the vector.

QValueVector::const_iterator
       The vector's const iterator type.

QValueVector::const_pointer
       The const pointer to T type.

QValueVector::const_reference
       The const reference to T type.

QValueVector::difference_type
       A signed integral type used to represent the distance between two iterators.

QValueVector::iterator
       The vector's iterator type.

QValueVector::pointer
       The pointer to T type.

QValueVector::reference
       The reference to T type.

QValueVector::size_type
       An unsigned integral type, used to represent various sizes.

QValueVector::value_type
       The type of the object stored in the vector.

MEMBER FUNCTION DOCUMENTATION
QValueVector::QValueVector ()
       Constructs an empty vector without any elements. To create a vector which reserves an
       initial amount of space for elements, use QValueVector(size_type n).

QValueVector::QValueVector ( const QValueVector<T> & v )
       Constructs a copy of v.

       This operation costs O(1) time because QValueVector is implicitly shared.

       The first modification to the vector does takes O(n) time, because the elements must be
       copied.

QValueVector::QValueVector ( size_type n, const T & val = T ( ) )
       Constructs a vector with an initial size of n elements. Each element is initialized with
       the value of val.

QValueVector::QValueVector ( std::vector<T> & v )
       Constructs a copy of v.

QValueVector::QValueVector ( const std::vector<T> & v )
       This operation costs O(n) time because v is copied.

QValueVector::~QValueVector ()
       Destroys the vector, destroying all elements and freeing the allocated memory. References
       to the values in the vector and all iterators of this vector become invalidated. Note that
       it is impossible for an iterator to check whether or not it is valid: QValueVector is
       tuned for performance, not for error checking.

void QValueVector::append ( const T & x )
       Appends a copy of x to the end of the vector.

       See also push_back() and insert().

reference QValueVector::at ( size_type i, bool * ok = 0 )
       Returns a reference to the element with index i. If ok is non-null, and the index i is out
       of range, *ok is set to FALSE and the returned reference is undefined. If the index i is
       within the range of the vector, and ok is non-null, *ok is set to TRUE and the returned
       reference is well defined.

const_reference QValueVector::at ( size_type i, bool * ok = 0 ) const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a const reference to the element with index i. If ok is non-null, and the index i
       is out of range, *ok is set to FALSE and the returned reference is undefined. If the index
       i is within the range of the vector, and ok is non-null, *ok is set to TRUE and the
       returned reference is well defined.

reference QValueVector::back ()
       Returns a reference to the last element in the vector. If there is no last element, this
       function has undefined behavior.

       See also empty() and front().

const_reference QValueVector::back () const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a const reference to the last element in the vector. If there is no last element,
       this function has undefined behavior.

       See also empty() and front().

iterator QValueVector::begin ()
       Returns an iterator pointing to the beginning of the vector. If the vector is empty(), the
       returned iterator will equal end().

const_iterator QValueVector::begin () const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a const iterator pointing to the beginning of the vector. If the vector is
       empty(), the returned iterator will equal end().

size_type QValueVector::capacity () const
       Returns the maximum number of elements that can be stored in the vector without forcing
       memory reallocation. If memory reallocation takes place, some or all iterators may become
       invalidated.

void QValueVector::clear ()
       Removes all the elements from the vector.

size_type QValueVector::count () const
       Returns the number of items in the vector.

       See also isEmpty().

bool QValueVector::empty () const
       Returns TRUE if the vector is empty; otherwise returns FALSE. Equivalent to size()==0,
       only faster.

       This function is provided for STL compatibility. It is equivalent to isEmpty().

       See also size().

iterator QValueVector::end ()
       Returns an iterator pointing behind the last element of the vector.

const_iterator QValueVector::end () const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a const iterator pointing behind the last element of the vector.

iterator QValueVector::erase ( iterator pos )
       Removes the element at position pos and returns the position of the next element.

iterator QValueVector::erase ( iterator first, iterator last )
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Removes all elements from first up to but not including last and returns the position of
       the next element.

reference QValueVector::first ()
       Returns a reference to the first item in the vector. If there is no first item, this
       function has undefined behavior.

       See also empty() and last().

const_reference QValueVector::first () const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

reference QValueVector::front ()
       Returns a reference to the first element in the vector. If there is no first element, this
       function has undefined behavior.

       See also empty() and back().

const_reference QValueVector::front () const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a const reference to the first element in the vector. If there is no first
       element, this function has undefined behavior.

       See also empty() and back().

iterator QValueVector::insert ( iterator pos, const T & x )
       Inserts a copy of x at the position immediately before pos.

       See also push_back().

iterator QValueVector::insert ( iterator pos, size_type n, const T & x )
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Inserts n copies of x immediately before position x.

       See also push_back().

bool QValueVector::isEmpty () const
       Returns TRUE if the vector is empty; returns FALSE otherwise.

       See also count().

reference QValueVector::last ()
       Returns a reference to the last item in the vector. If there is no last item, this
       function has undefined behavior.

       See also empty() and first().

const_reference QValueVector::last () const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

QValueVector<;T> & QValueVector::operator= ( const QValueVector<T> & v )
       Assigns v to this vector and returns a reference to this vector.

       All iterators of the current vector become invalidated by this operation. The cost of such
       an assignment is O(1) since QValueVector is implicitly shared.

QValueVector<;T> & QValueVector::operator= ( const std::vector<T> & v )
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Assigns v to this vector and returns a reference to this vector.

       All iterators of the current vector become invalidated by this operation. The cost of this
       assignment is O(n) since v is copied.

bool QValueVector::operator== ( const QValueVector<T> & x ) const
       Returns TRUE if each element in this vector equals each corresponding element in x;
       otherwise returns FALSE.

bool QValueVector::operator== ( const QValueVector<T> & x )
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns TRUE if each element in this vector equals each corresponding element in x;
       otherwise returns FALSE.

reference QValueVector::operator[] ( size_type i )
       Returns a reference to the element at index i. If i is out of range, this function has
       undefined behavior.

       See also at().

const_reference QValueVector::operator[] ( size_type i ) const
       This is an overloaded member function, provided for convenience. It behaves essentially
       like the above function.

       Returns a const reference to the element at index i. If i is out of range, this function
       has undefined behavior.

       See also at().

void QValueVector::pop_back ()
       Removes the last item from the vector.

       This function is provided for STL compatibility.

void QValueVector::push_back ( const T & x )
       Appends a copy of x to the end of the vector. This is the fastest way to add new elements.

       This function is provided for STL compatibility. It is equivalent to append().

       See also insert().

void QValueVector::reserve ( size_type n )
       Increases the vector's capacity. If n is less than or equal to capacity(), nothing
       happens. Otherwise, additional memory is allocated so that capacity() will be increased to
       a value greater than or equal to n. All iterators will then become invalidated. Note that
       the vector's size() and the values of existing elements remain unchanged.

void QValueVector::resize ( size_type n, const T & val = T ( ) )
       Changes the size of the vector to n. If n is greater than the current size(), elements are
       added to the end and initialized with the value of val. If n is less than size(), elements
       are removed from the end. If n is equal to size() nothing happens.

size_type QValueVector::size () const
       Returns the number of elements in the vector.

       This function is provided for STL compatibility. It is equivalent to count().

       See also empty().

SEE ALSO
       http://doc.trolltech.com/qvaluevector.html http://www.trolltech.com/faq/tech.html

COPYRIGHT
       Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the license file included
       in the distribution for a complete license statement.

AUTHOR
       Generated automatically from the source code.

BUGS
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is located at
       $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. This man page is
       provided as a convenience for those users who prefer man pages, although this format is
       not officially supported by Trolltech.

       If you find errors in this manual page, please report them to qt-bugs@trolltech.com.
       Please include the name of the manual page (qvaluevector.3qt) and the Qt version (3.1.1).

Trolltech AS				 9 December 2002			QValueVector(3qt)


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