Contents

• Public Functions
• Detailed Description

Detailed Description

TheQSetIterator class provides a Java-style const iterator forQSet.

QSet supports bothJava-style iterators andSTL-style iterators. 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.

QSetIterator<T> allows you to iterate over aQSet<T>. If you want to modify the set as you iterate over it, useQMutableSetIterator<T> instead.

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

QSet<QString> set;...QSetIterator<QString> i(set);while (i.hasNext())qDebug()<< i.next();

Thenext() function returns the next item in the set and advances the iterator. Unlike STL-style iterators, Java-style iterators pointbetween items rather than directlyat items. The first call tonext() advances the iterator to the position between the first and second item, and returns the first item; the second call tonext() 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:

QSetIterator<QString> i(set);i.toBack();while (i.hasPrevious())qDebug()<< i.previous();

If you want to find all occurrences of a particular value, usefindNext() orfindPrevious() in a loop.

Multiple iterators can be used on the same set. If the set is modified while aQSetIterator is active, theQSetIterator will continue iterating over the original set, ignoring the modified copy.

Member Function Documentation

QSetIterator::QSetIterator(constQSet<T> & set)

Constructs an iterator for traversingset. The iterator is set to be at the front of the set (before the first item).

See alsooperator=().

bool QSetIterator::findNext(constT & value)

Searches forvalue starting from the current iterator position forward. Returns true ifvalue is found; otherwise returns false.

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

See alsofindPrevious().

bool QSetIterator::findPrevious(constT & value)

Searches forvalue starting from the current iterator position backward. Returns true ifvalue is found; otherwise returns false.

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

See alsofindNext().

bool QSetIterator::hasNext() const

Returns true if there is at least one item ahead of the iterator, i.e. the iterator isnot at the back of the container; otherwise returns false.

See alsohasPrevious() andnext().

bool QSetIterator::hasPrevious() const

Returns true if there is at least one item behind the iterator, i.e. the iterator isnot at the front of the container; otherwise returns false.

See alsohasNext() andprevious().

constT & QSetIterator::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.

See alsohasNext(),peekNext(), andprevious().

constT & QSetIterator::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.

See alsohasNext(),next(), andpeekPrevious().

constT & QSetIterator::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.

See alsohasPrevious(),previous(), andpeekNext().

constT & QSetIterator::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.

See alsohasPrevious(),peekPrevious(), andnext().

void QSetIterator::toBack()

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

See alsotoFront() andprevious().

void QSetIterator::toFront()

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

See alsotoBack() andnext().

QSetIterator & QSetIterator::operator=(constQSet<T> & set)

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

See alsotoFront() andtoBack().