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The QSet::const_iterator class provides an STL-style const iterator for QSet. More...
#include <QSet>
The QSet::const_iterator class provides an STL-style const iterator for QSet.
QSet features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.
QSet<T>::const_iterator allows you to iterate over a QSet<T>. There is no corresponding non-const iterators, because changing a value stored in a QSet would potentially require moving the value in the internal hash table used by QSet.
The default QSet::const_iterator constructor creates an uninitialized iterator. You must initialize it using a function like QSet::begin(), QSet::end(), or QSet::insert() before you can start iterating. Here's a typical loop that prints all the items stored in a set:
QSet<QString> set; set << "January" << "February" << ... << "December"; QSet<QString>::const_iterator i; for (i = set.begin(); i != set.end(); ++i) qDebug() << *i;
STL-style iterators can be used as arguments to generic algorithms. For example, here's how to find an item in the set using the qFind() algorithm:
QSet<QString> set; ... QSet<QString>::iterator it = qFind(set.begin(), set.end(), "Jeanette"); if (it != set.constEnd()) cout << "Found Jeanette" << endl;
Multiple iterators can be used on the same set. However, you may not attempt to modify the container while iterating on it.
See also QSetIterator.
Constructs an uninitialized iterator.
Functions like operator*() and operator++() should not be called on an uninitialized iterartor. Use operator=() to assign a value to it before using it.
See also QSet::constBegin() and QSet::constEnd().
Constructs a copy of other.
Returns true if other points to a different item than this iterator; otherwise returns false.
See also operator==().
Returns a reference to the current item.
See also operator->().
Returns an iterator to the item at j positions forward from this iterator. (If j is negative, the iterator goes backward.)
This operation can be slow for large j values.
See also operator-().
The prefix ++ operator (++it) advances the iterator to the next item in the set and returns an iterator to the new current item.
Calling this function on QSet::constEnd() leads to undefined results.
See also operator--().
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
The postfix ++ operator (it++) advances the iterator to the next item in the set and returns an iterator to the previously current item.
Advances the iterator by j items. (If j is negative, the iterator goes backward.)
This operation can be slow for large j values.
See also operator-=() and operator+().
Returns an iterator to the item at j positions backward from this iterator. (If j is negative, the iterator goes forward.)
This operation can be slow for large j values.
See also operator+().
The prefix -- operator (--it) makes the preceding item current and returns an iterator to the new current item.
Calling this function on QSet::begin() leads to undefined results.
See also operator++().
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
The postfix -- operator (it--) makes the preceding item current and returns an iterator to the previously current item.
Makes the iterator go back by j items. (If j is negative, the iterator goes forward.)
This operation can be slow for large j values.
See also operator+=() and operator-().
Returns a pointer to the current item.
See also operator*().
Assigns other to this iterator.
Returns true if other points to the same item as this iterator; otherwise returns false.
See also operator!=().
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