內容

• 公共函數
• 詳細描述

QVectorIterator Class

The QVectorIterator 類提供 Java 樣式常量迭代器為 QVector and QStack . 更多...

頭：	#include <QVectorIterator>
qmake:	QT += core

• 所有成員列錶，包括繼承成員

公共函數

	QVectorIterator (const QVector<T> & vector )
bool	findNext (const T & value )
bool	findPrevious (const T & value )
bool	hasNext () const
bool	hasPrevious () const
const T &	next ()
const T &	peekNext () const
const T &	peekPrevious () const
const T &	previous ()
void	toBack ()
void	toFront ()
QVectorIterator &	operator= (const QVector<T> & vector )

詳細描述

The QVectorIterator 類提供 Java 樣式常量迭代器為 QVector and QStack .

QVector 同時擁有 Java 風格迭代器 and STL 樣式迭代器 . The Java-style iterators are more high-level and easier to use than the STL-style iterators; on the other hand, they are slightly less efficient.

An alternative to using iterators is to use index positions. Most QVector member functions take an index as their first parameter, making it possible to access, insert, and remove items without using iterators.

QVectorIterator <T> allows you to iterate over a QVector <T> (or a QStack <T>). If you want to modify the vector as you iterate over it, use QMutableVectorIterator <T> 代替。

The QVectorIterator constructor takes a QVector as argument. After construction, the iterator is located at the very beginning of the vector (before the first item). Here's how to iterate over all the elements sequentially:

QVector<float> vector;
...
QVectorIterator<float> i(vector);
while (i.hasNext())
    qDebug() << i.next();
					

The next () function returns the next item in the vector and advances the iterator. Unlike STL-style iterators, Java-style iterators point between items rather than directly at items. The first call to next () advances the iterator to the position between the first and second item, and returns the first item; the second call to next () advances the iterator to the position between the second and third item, returning the second item; and so on.

Here's how to iterate over the elements in reverse order:

QVectorIterator<float> i(vector);
i.toBack();
while (i.hasPrevious())
    qDebug() << i.previous();
					

If you want to find all occurrences of a particular value, use findNext () 或 findPrevious () in a loop.

Multiple iterators can be used on the same vector. If the vector is modified while a QVectorIterator is active, the QVectorIterator will continue iterating over the original vector, ignoring the modified copy.

另請參閱 QMutableVectorIterator and QVector::const_iterator .

成員函數文檔編製

QVectorIterator:: QVectorIterator (const QVector < T > & vector )

構造迭代器為遍曆 vector . The iterator is set to be at the front of the vector (before the first item).

另請參閱 operator= ().

bool QVectorIterator:: findNext (const T & value )

搜索 value starting from the current iterator position forward. Returns true if value is found; otherwise returns false .

After the call, if value was found, the iterator is positioned just after the matching item; otherwise, the iterator is positioned at the back of the container.

另請參閱 findPrevious ().

bool QVectorIterator:: findPrevious (const T & value )

搜索 value starting from the current iterator position backward. Returns true if value is found; otherwise returns false.

After the call, if value was found, the iterator is positioned just before the matching item; otherwise, the iterator is positioned at the front of the container.

另請參閱 findNext ().

bool QVectorIterator:: hasNext () const

返迴 true if there is at least one item ahead of the iterator, i.e. the iterator is not at the back of the container; otherwise returns false .

另請參閱 hasPrevious () 和 next ().

bool QVectorIterator:: hasPrevious () const

返迴 true if there is at least one item behind the iterator, i.e. the iterator is not at the front of the container; otherwise returns false .

另請參閱 hasNext () 和 previous ().

const T &QVectorIterator:: next ()

Returns the next item and advances the iterator by one position.

Calling this function on an iterator located at the back of the container leads to undefined results.

另請參閱 hasNext (), peekNext ()，和 previous ().

const T &QVectorIterator:: peekNext () const

Returns the next item without moving the iterator.

Calling this function on an iterator located at the back of the container leads to undefined results.

另請參閱 hasNext (), next ()，和 peekPrevious ().

const T &QVectorIterator:: peekPrevious () const

Returns the previous item without moving the iterator.

Calling this function on an iterator located at the front of the container leads to undefined results.

另請參閱 hasPrevious (), previous ()，和 peekNext ().

const T &QVectorIterator:: previous ()

Returns the previous item and moves the iterator back by one position.

Calling this function on an iterator located at the front of the container leads to undefined results.

另請參閱 hasPrevious (), peekPrevious ()，和 next ().

void QVectorIterator:: toBack ()

Moves the iterator to the back of the container (after the last item).

另請參閱 toFront () 和 previous ().

void QVectorIterator:: toFront ()

Moves the iterator to the front of the container (before the first item).

另請參閱 toBack () 和 next ().

QVectorIterator &QVectorIterator:: operator= (const QVector < T > & vector )

Makes the iterator operate on vector . The iterator is set to be at the front of the vector (before the first item).

另請參閱 toFront () 和 toBack ().