QVector Class

The QVector class is a template class that provides a dynamic array.

All functions in this class are reentrant.

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Publié le 27 décembre 2024 - Mis à jour le 27 décembre 2024

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QVector Class▲

Header: QVector
qmake: QT += core
Inherited By: QPolygon, QPolygonF, QStack, QVulkanInfoVector, and QXmlStreamAttributes
Group: QVector is part of tools, Implicitly Shared Classes

Detailed Description▲

QVector<T> is one of Qt's generic container classes. It stores its items in adjacent memory locations and provides fast index-based access.

QList<T>, QLinkedList<T>, QVector<T>, and QVarLengthArray<T> provide similar APIs and functionality. They are often interchangeable, but there are performance consequences. Here is an overview of use cases:

QVector should be your default first choice. QVector<T> will usually give better performance than QList<T>, because QVector<T> always stores its items sequentially in memory, where QList<T> will allocate its items on the heap unless sizeof(T) <= sizeof(void*) and T has been declared to be either a Q_MOVABLE_TYPE or a Q_PRIMITIVE_TYPE using Q_DECLARE_TYPEINFO. See the Pros and Cons of Using QList for an explanation.
However, QList is used throughout the Qt APIs for passing parameters and for returning values. Use QList to interface with those APIs.
If you need a real linked list, which guarantees constant time insertions mid-list and uses iterators to items rather than indexes, use QLinkedList.

QVector and QVarLengthArray both guarantee C-compatible array layout. QList does not. This might be important if your application must interface with a C API.

Iterators into a QLinkedList and references into heap-allocating QLists remain valid as long as the referenced items remain in the container. This is not true for iterators and references into a QVector and non-heap-allocating QLists.

Here's an example of a QVector that stores integers and a QVector that stores QString values:

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QVector&lt;int&gt; integerVector;
QVector&lt;QString&gt; stringVector;

QVector stores its items in a vector (array). Typically, vectors are created with an initial size. For example, the following code constructs a QVector with 200 elements:

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QVector&lt;QString&gt; vector(200);

The elements are automatically initialized with a default-constructed value. If you want to initialize the vector with a different value, pass that value as the second argument to the constructor:

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QVector&lt;QString&gt; vector(200, "Pass");

You can also call fill() at any time to fill the vector with a value.

QVector uses 0-based indexes, just like C++ arrays. To access the item at a particular index position, you can use operator[](). On non-const vectors, operator[]() returns a reference to the item that can be used on the left side of an assignment:

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if (vector[0] == "Liz")
    vector[0] = "Elizabeth";

For read-only access, an alternative syntax is to use at():

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for (int i = 0; i &lt; vector.size(); ++i) {
    if (vector.at(i) == "Alfonso")
        cout &lt;&lt; "Found Alfonso at position " &lt;&lt; i &lt;&lt; endl;
}

at() can be faster than operator[](), because it never causes a deep copy to occur.

Another way to access the data stored in a QVector is to call data(). The function returns a pointer to the first item in the vector. You can use the pointer to directly access and modify the elements stored in the vector. The pointer is also useful if you need to pass a QVector to a function that accepts a plain C++ array.

If you want to find all occurrences of a particular value in a vector, use indexOf() or lastIndexOf(). The former searches forward starting from a given index position, the latter searches backward. Both return the index of the matching item if they found one; otherwise, they return -1. For example:

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int i = vector.indexOf("Harumi");
if (i != -1)
    cout &lt;&lt; "First occurrence of Harumi is at position " &lt;&lt; i &lt;&lt; endl;

If you simply want to check whether a vector contains a particular value, use contains(). If you want to find out how many times a particular value occurs in the vector, use count().

QVector provides these basic functions to add, move, and remove items: insert(), replace(), remove(), prepend(), append(). With the exception of append() and replace(), these functions can be slow (linear time) for large vectors, because they require moving many items in the vector by one position in memory. If you want a container class that provides fast insertion/removal in the middle, use QList or QLinkedList instead.

Unlike plain C++ arrays, QVectors can be resized at any time by calling resize(). If the new size is larger than the old size, QVector might need to reallocate the whole vector. QVector tries to reduce the number of reallocations by preallocating up to twice as much memory as the actual data needs.

If you know in advance approximately how many items the QVector will contain, you can call reserve(), asking QVector to preallocate a certain amount of memory. You can also call capacity() to find out how much memory QVector actually allocated.

Note that using non-const operators and functions can cause QVector to do a deep copy of the data. This is due to implicit sharing.

QVector's value type must be an assignable data type. This covers most data types that are commonly used, but the compiler won't let you, for example, store a QWidget as a value; instead, store a QWidget *. A few functions have additional requirements; for example, indexOf() and lastIndexOf() expect the value type to support operator==(). These requirements are documented on a per-function basis.

Like the other container classes, QVector provides Java-style iterators (QVectorIterator and QMutableVectorIterator) and STL-style iterators (QVector::const_iterator and QVector::iterator). In practice, these are rarely used, because you can use indexes into the QVector.

In addition to QVector, Qt also provides QVarLengthArray, a very low-level class with little functionality that is optimized for speed.

QVector does not support inserting, prepending, appending or replacing with references to its own values. Doing so will cause your application to abort with an error message.

More Information on Using Qt Containers▲

For a detailed discussion comparing Qt containers with each other and with STL containers, see Understand the Qt Containers.

Member Type Documentation▲

QVector::ConstIterator▲

Qt-style synonym for QVector::const_iterator.

QVector::Iterator▲

Qt-style synonym for QVector::iterator.

QVector::const_iterator▲

The QVector::const_iterator typedef provides an STL-style const iterator for QVector and QStack.

QVector provides both STL-style iterators and Java-style iterators. The STL-style const iterator is simply a typedef for "const T *" (pointer to const T).

Iterators on implicitly shared containers do not work exactly like STL-iterators. You should avoid copying a container while iterators are active on that container. For more information, read Implicit sharing iterator problem.

QVector::const_pointer▲

Typedef for const T *. Provided for STL compatibility.

QVector::const_reference▲

Typedef for T &. Provided for STL compatibility.

[since 5.6] QVector::const_reverse_iterator▲

The QVector::const_reverse_iterator typedef provides an STL-style const reverse iterator for QVector.

It is simply a typedef for std::reverse_iterator<const T*>.

This typedef was introduced in Qt 5.6.

QVector::difference_type▲

Typedef for ptrdiff_t. Provided for STL compatibility.

QVector::iterator▲

The QVector::iterator typedef provides an STL-style non-const iterator for QVector and QStack.

QVector provides both STL-style iterators and Java-style iterators. The STL-style non-const iterator is simply a typedef for "T *" (pointer to T).

QVector::pointer▲

Typedef for T *. Provided for STL compatibility.

QVector::reference▲

Typedef for T &. Provided for STL compatibility.

[since 5.6] QVector::reverse_iterator▲

The QVector::reverse_iterator typedef provides an STL-style non-const reverse iterator for QVector.

It is simply a typedef for std::reverse_iterator<T*>.

This typedef was introduced in Qt 5.6.

QVector::size_type▲

Typedef for int. Provided for STL compatibility.

QVector::value_type▲

Typedef for T. Provided for STL compatibility.

Member Function Documentation▲

void QVector::prepend(T &&value)▲

void QVector::prepend(const T &value)

Inserts value at the beginning of the vector.

Example:

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QVector&lt;QString&gt; vector;
vector.prepend("one");
vector.prepend("two");
vector.prepend("three");
// vector: ["three", "two", "one"]

This is the same as vector.insert(0, value).

For large vectors, this operation can be slow (linear time), because it requires moving all the items in the vector by one position further in memory. If you want a container class that provides a fast prepend() function, use QList or QLinkedList instead.

void QVector::insert(int i, T &&value)▲

void QVector::insert(int i, const T &value)

Inserts value at index position i in the vector. If i is 0, the value is prepended to the vector. If i is size(), the value is appended to the vector.

Example:

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QVector&lt;QString&gt; vector;
vector &lt;&lt; "alpha" &lt;&lt; "beta" &lt;&lt; "delta";
vector.insert(2, "gamma");
// vector: ["alpha", "beta", "gamma", "delta"]

For large vectors, this operation can be slow (linear time), because it requires moving all the items at indexes i and above by one position further in memory. If you want a container class that provides a fast insert() function, use QLinkedList instead.

QVector::iterator QVector::insert(QVector::iterator before, T &&value)▲

QVector::iterator QVector::insert(QVector::iterator before, const T &value)

This is an overloaded function.

Inserts value in front of the item pointed to by the iterator before. Returns an iterator pointing at the inserted item.

void QVector::push_front(T &&value)▲

void QVector::push_front(const T &value)

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

QVector::QVector()▲

Constructs an empty vector.

[explicit] QVector::QVector(int size)▲

Constructs a vector with an initial size of size elements.

The elements are initialized with a default-constructed value.

QVector::QVector(int size, const T &value)▲

Constructs a vector with an initial size of size elements. Each element is initialized with value.

QVector::QVector(const QVector<T> &other)▲

Constructs a copy of other.

This operation takes constant time, because QVector is implicitly shared. This makes returning a QVector from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), and that takes linear time.

[since 5.2] QVector::QVector(QVector<T> &&other)▲

Move-constructs a QVector instance, making it point at the same object that other was pointing to.

This function was introduced in Qt 5.2.

[since 4.8] QVector::QVector(std::initializer_list<T> args)▲

Constructs a vector from the std::initializer_list given by args.

This constructor is only enabled if the compiler supports C++11 initializer lists.

This function was introduced in Qt 4.8.

QVector::~QVector()▲

Destroys the vector.

void QVector::append(const T &value)▲

Inserts value at the end of the vector.

Example:

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QVector&lt;QString&gt; vector;
vector.append("one");
vector.append("two");
QString three = "three";
vector.append(three);
// vector: ["one", "two", "three"]
// three: "three"

This is the same as calling resize(size() + 1) and assigning value to the new last element in the vector.

This operation is relatively fast, because QVector typically allocates more memory than necessary, so it can grow without reallocating the entire vector each time.

[since 5.6] void QVector::append(T &&value)▲

This is an overloaded function.

Example:

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QVector&lt;QString&gt; vector;
vector.append("one");
vector.append("two");
QString three = "three";
vector.append(std::move(three));
// vector: ["one", "two", "three"]
// three: ""

This function was introduced in Qt 5.6.

[since 5.5] void QVector::append(const QVector<T> &value)▲

This is an overloaded function.

Appends the items of the value vector to this vector.

This function was introduced in Qt 5.5.

const T &QVector::at(int i) const▲

Returns the item at index position i in the vector.

i must be a valid index position in the vector (i.e., 0 <= i < size()).

QVector::reference QVector::back()▲

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

QVector::const_reference QVector::back() const▲

This is an overloaded function.

QVector::iterator QVector::begin()▲

Returns an STL-style iterator pointing to the first item in the vector.

QVector::const_iterator QVector::begin() const▲

This is an overloaded function.

int QVector::capacity() const▲

Returns the maximum number of items that can be stored in the vector without forcing a reallocation.

The sole purpose of this function is to provide a means of fine tuning QVector's memory usage. In general, you will rarely ever need to call this function. If you want to know how many items are in the vector, call size().

[since 5.0] QVector::const_iterator QVector::cbegin() const▲

Returns a const STL-style iterator pointing to the first item in the vector.

This function was introduced in Qt 5.0.

[since 5.0] QVector::const_iterator QVector::cend() const▲

Returns a const STL-style iterator pointing to the imaginary item after the last item in the vector.

This function was introduced in Qt 5.0.

void QVector::clear()▲

Removes all the elements from the vector.

Until Qt 5.6, this also released the memory used by the vector. From Qt 5.7, the capacity is preserved. To shed all capacity, swap with a default-constructed vector:

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QVector&lt;T&gt; v ...;
QVector&lt;T&gt;().swap(v);
Q_ASSERT(v.capacity() == 0);

or call squeeze().

QVector::const_iterator QVector::constBegin() const▲

Returns a const STL-style iterator pointing to the first item in the vector.

const T *QVector::constData() const▲

Returns a const pointer to the data stored in the vector. The pointer can be used to access the items in the vector. The pointer remains valid as long as the vector isn't reallocated.

This function is mostly useful to pass a vector to a function that accepts a plain C++ array.

QVector::const_iterator QVector::constEnd() const▲

Returns a const STL-style iterator pointing to the imaginary item after the last item in the vector.

[since 5.6] const T &QVector::constFirst() const▲

Returns a const reference to the first item in the vector. This function assumes that the vector isn't empty.

This function was introduced in Qt 5.6.

[since 5.6] const T &QVector::constLast() const▲

Returns a const reference to the last item in the vector. This function assumes that the vector isn't empty.

This function was introduced in Qt 5.6.

bool QVector::contains(const T &value) const▲

Returns true if the vector contains an occurrence of value; otherwise returns false.

This function requires the value type to have an implementation of operator==().

int QVector::count(const T &value) const▲

Returns the number of occurrences of value in the vector.

This function requires the value type to have an implementation of operator==().

int QVector::count() const▲

This is an overloaded function.

Same as size().

[since 5.6] QVector::const_reverse_iterator QVector::crbegin() const▲

Returns a const STL-style reverse iterator pointing to the first item in the vector, in reverse order.

This function was introduced in Qt 5.6.

[since 5.6] QVector::const_reverse_iterator QVector::crend() const▲

Returns a const STL-style reverse iterator pointing to one past the last item in the vector, in reverse order.

This function was introduced in Qt 5.6.

T *QVector::data()▲

Returns a pointer to the data stored in the vector. The pointer can be used to access and modify the items in the vector.

Example:

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QVector&lt;int&gt; vector(10);
int *data = vector.data();
for (int i = 0; i &lt; 10; ++i)
    data[i] = 2 * i;

The pointer remains valid as long as the vector isn't reallocated.

This function is mostly useful to pass a vector to a function that accepts a plain C++ array.

const T *QVector::data() const▲

This is an overloaded function.

bool QVector::empty() const▲

This function is provided for STL compatibility. It is equivalent to isEmpty(), returning true if the vector is empty; otherwise returns false.

QVector::iterator QVector::end()▲

Returns an STL-style iterator pointing to the imaginary item after the last item in the vector.

QVector::const_iterator QVector::end() const▲

This is an overloaded function.

[since 4.5] bool QVector::endsWith(const T &value) const▲

Returns true if this vector is not empty and its last item is equal to value; otherwise returns false.

This function was introduced in Qt 4.5.

QVector::iterator QVector::erase(QVector::iterator pos)▲

Removes the item pointed to by the iterator pos from the vector, and returns an iterator to the next item in the vector (which may be end()).

QVector::iterator QVector::erase(QVector::iterator begin, QVector::iterator end)▲

This is an overloaded function.

Removes all the items from begin up to (but not including) end. Returns an iterator to the same item that end referred to before the call.

QVector<T> &QVector::fill(const T &value, int size = -1)▲

Assigns value to all items in the vector. If size is different from -1 (the default), the vector is resized to size size beforehand.

Example:

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QVector&lt;QString&gt; vector(3);
vector.fill("Yes");
// vector: ["Yes", "Yes", "Yes"]

vector.fill("oh", 5);
// vector: ["oh", "oh", "oh", "oh", "oh"]

T &QVector::first()▲

Returns a reference to the first item in the vector. This function assumes that the vector isn't empty.

const T &QVector::first() const▲

This is an overloaded function.

[static] QVector<T> QVector::fromList(const QList<T> &list)▲

Returns a QVector object with the data contained in list.

Example:

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QStringList list;
list &lt;&lt; "Sven" &lt;&lt; "Kim" &lt;&lt; "Ola";

QVector&lt;QString&gt; vect = QVector&lt;QString&gt;::fromList(list);
// vect: ["Sven", "Kim", "Ola"]

[static] QVector<T> QVector::fromStdVector(const std::vector<T> &vector)▲

Returns a QVector object with the data contained in vector. The order of the elements in the QVector is the same as in vector.

Example:

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std::vector&lt;double&gt; stdvector;
vector.push_back(1.2);
vector.push_back(0.5);
vector.push_back(3.14);

QVector&lt;double&gt; vector = QVector&lt;double&gt;::fromStdVector(stdvector);

T &QVector::front()▲

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

QVector::const_reference QVector::front() const▲

This is an overloaded function.

int QVector::indexOf(const T &value, int from = 0) const▲

Returns the index position of the first occurrence of value in the vector, searching forward from index position from. Returns -1 if no item matched.

Example:

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QVector&lt;QString&gt; vector;
vector &lt;&lt; "A" &lt;&lt; "B" &lt;&lt; "C" &lt;&lt; "B" &lt;&lt; "A";
vector.indexOf("B");            // returns 1
vector.indexOf("B", 1);         // returns 1
vector.indexOf("B", 2);         // returns 3
vector.indexOf("X");            // returns -1

This function requires the value type to have an implementation of operator==().

void QVector::insert(int i, int count, const T &value)▲

This is an overloaded function.

Inserts count copies of value at index position i in the vector.

Example:

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QVector&lt;double&gt; vector;
vector &lt;&lt; 2.718 &lt;&lt; 1.442 &lt;&lt; 0.4342;
vector.insert(1, 3, 9.9);
// vector: [2.718, 9.9, 9.9, 9.9, 1.442, 0.4342]

QVector::iterator QVector::insert(QVector::iterator before, int count, const T &value)▲

Inserts count copies of value in front of the item pointed to by the iterator before. Returns an iterator pointing at the first of the inserted items.

bool QVector::isEmpty() const▲

Returns true if the vector has size 0; otherwise returns false.

T &QVector::last()▲

Returns a reference to the last item in the vector. This function assumes that the vector isn't empty.

const T &QVector::last() const▲

This is an overloaded function.

int QVector::lastIndexOf(const T &value, int from = -1) const▲

Returns the index position of the last occurrence of the value value in the vector, searching backward from index position from. If from is -1 (the default), the search starts at the last item. Returns -1 if no item matched.

Example:

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QList&lt;QString&gt; vector;
vector &lt;&lt; "A" &lt;&lt; "B" &lt;&lt; "C" &lt;&lt; "B" &lt;&lt; "A";
vector.lastIndexOf("B");        // returns 3
vector.lastIndexOf("B", 3);     // returns 3
vector.lastIndexOf("B", 2);     // returns 1
vector.lastIndexOf("X");        // returns -1

This function requires the value type to have an implementation of operator==().

[since 5.2] int QVector::length() const▲

Same as size() and count().

Provided for compatibility with QList.

This function was introduced in Qt 5.2.

QVector<T> QVector::mid(int pos, int length = -1) const▲

Returns a sub-vector which contains elements from this vector, starting at position pos. If length is -1 (the default), all elements after pos are included; otherwise length elements (or all remaining elements if there are less than length elements) are included.

[since 5.6] void QVector::move(int from, int to)▲

Moves the item at index position from to index position to.

Provided for compatibility with QList.

This function was introduced in Qt 5.6.

void QVector::pop_back()▲

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

void QVector::pop_front()▲

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

void QVector::push_back(const T &value)▲

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

[since 5.6] void QVector::push_back(T &&value)▲

This is an overloaded function.

This function was introduced in Qt 5.6.

[since 5.6] QVector::reverse_iterator QVector::rbegin()▲

Returns a STL-style reverse iterator pointing to the first item in the vector, in reverse order.

This function was introduced in Qt 5.6.

[since 5.6] QVector::const_reverse_iterator QVector::rbegin() const▲

This is an overloaded function.

This function was introduced in Qt 5.6.

void QVector::remove(int i)▲

This is an overloaded function.

Removes the element at index position i.

void QVector::remove(int i, int count)▲

This is an overloaded function.

Removes count elements from the middle of the vector, starting at index position i.

[since 5.4] int QVector::removeAll(const T &t)▲

Removes all elements that compare equal to t from the vector. Returns the number of elements removed, if any.

Provided for compatibility with QList.

This function was introduced in Qt 5.4.

[since 5.2] void QVector::removeAt(int i)▲

Removes the element at index position i. Equivalent to

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remove(i);

Provided for compatibility with QList.

This function was introduced in Qt 5.2.

[since 5.1] void QVector::removeFirst()▲

Removes the first item in the vector. Calling this function is equivalent to calling remove(0). The vector must not be empty. If the vector can be empty, call isEmpty() before calling this function.

This function was introduced in Qt 5.1.

[since 5.1] void QVector::removeLast()▲

Removes the last item in the vector. Calling this function is equivalent to calling remove(size() - 1). The vector must not be empty. If the vector can be empty, call isEmpty() before calling this function.

This function was introduced in Qt 5.1.

[since 5.4] bool QVector::removeOne(const T &t)▲

Removes the first element that compares equal to t from the vector. Returns whether an element was, in fact, removed.

Provided for compatibility with QList.

This function was introduced in Qt 5.4.

[since 5.6] QVector::reverse_iterator QVector::rend()▲

Returns a STL-style reverse iterator pointing to one past the last item in the vector, in reverse order.

This function was introduced in Qt 5.6.

[since 5.6] QVector::const_reverse_iterator QVector::rend() const▲

This is an overloaded function.

This function was introduced in Qt 5.6.

void QVector::replace(int i, const T &value)▲

Replaces the item at index position i with value.

i must be a valid index position in the vector (i.e., 0 <= i < size()).

void QVector::reserve(int size)▲

Attempts to allocate memory for at least size elements. If you know in advance how large the vector will be, you should call this function to prevent reallocations and memory fragmentation.

If size is an underestimate, the worst that will happen is that the QVector will be a bit slower. If size is an overestimate, you may have used more memory than the normal QVector growth strategy would have allocated—or you may have used less.

An alternative to reserve() is calling resize(). Whether or not that is faster than reserve() depends on the element type, because resize() default-constructs all elements, and requires assignment to existing entries rather than calling append(), which copy- or move-constructs. For simple types, like int or double, resize() is typically faster, but for anything more complex, you should prefer reserve().

If the size passed to resize() was underestimated, you run out of allocated space and into undefined behavior. This problem does not exist with reserve(), because it treats the size as just a hint.

void QVector::resize(int size)▲

Sets the size of the vector to size. If size is greater than the current size, elements are added to the end; the new elements are initialized with a default-constructed value. If size is less than the current size, elements are removed from the end.

Since Qt 5.6, resize() doesn't shrink the capacity anymore. To shed excess capacity, use squeeze().

[since 5.10] void QVector::shrink_to_fit()▲

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

This function was introduced in Qt 5.10.

int QVector::size() const▲

Returns the number of items in the vector.

void QVector::squeeze()▲

Releases any memory not required to store the items.

The sole purpose of this function is to provide a means of fine tuning QVector's memory usage. In general, you will rarely ever need to call this function.

[since 4.5] bool QVector::startsWith(const T &value) const▲

Returns true if this vector is not empty and its first item is equal to value; otherwise returns false.

This function was introduced in Qt 4.5.

[since 4.8] void QVector::swap(QVector<T> &other)▲

Swaps vector other with this vector. This operation is very fast and never fails.

This function was introduced in Qt 4.8.

[since 5.2] T QVector::takeAt(int i)▲

Removes the element at index position i and returns it.

Equivalent to

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T t = at(i);
remove(i);
return t;

Provided for compatibility with QList.

This function was introduced in Qt 5.2.

[since 5.1] T QVector::takeFirst()▲

Removes the first item in the vector and returns it. This function assumes the vector is not empty. To avoid failure, call isEmpty() before calling this function.

This function was introduced in Qt 5.1.

[since 5.1] T QVector::takeLast()▲

Removes the last item in the list and returns it. This function assumes the vector is not empty. To avoid failure, call isEmpty() before calling this function.

If you don't use the return value, removeLast() is more efficient.

This function was introduced in Qt 5.1.

QList<T> QVector::toList() const▲

Returns a QList object with the data contained in this QVector.

Example:

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QVector&lt;double&gt; vect;
vect &lt;&lt; "red" &lt;&lt; "green" &lt;&lt; "blue" &lt;&lt; "black";

QList&lt;double&gt; list = vect.toList();
// list: ["red", "green", "blue", "black"]

std::vector<T> QVector::toStdVector() const▲

Returns a std::vector object with the data contained in this QVector. Example:

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QVector&lt;double&gt; vector;
vector &lt;&lt; 1.2 &lt;&lt; 0.5 &lt;&lt; 3.14;

std::vector&lt;double&gt; stdvector = vector.toStdVector();

T QVector::value(int i) const▲

Returns the value at index position i in the vector.

If the index i is out of bounds, the function returns a default-constructed value. If you are certain that i is within bounds, you can use at() instead, which is slightly faster.

T QVector::value(int i, const T &defaultValue) const▲

This is an overloaded function.

If the index i is out of bounds, the function returns defaultValue.

bool QVector::operator!=(const QVector<T> &other) const▲

Returns true if other is not equal to this vector; otherwise returns false.

Two vectors are considered equal if they contain the same values in the same order.

This function requires the value type to have an implementation of operator==().

QVector<T> QVector::operator+(const QVector<T> &other) const▲

Returns a vector that contains all the items in this vector followed by all the items in the other vector.

QVector<T> &QVector::operator+=(const QVector<T> &other)▲

Appends the items of the other vector to this vector and returns a reference to this vector.

QVector<T> &QVector::operator+=(const T &value)▲

This is an overloaded function.

Appends value to the vector.

[since 5.11] QVector<T> &QVector::operator+=(T &&value)▲

This is an overloaded function.

This function was introduced in Qt 5.11.

QVector<T> &QVector::operator<<(const T &value)▲

Appends value to the vector and returns a reference to this vector.

QVector<T> &QVector::operator<<(const QVector<T> &other)▲

Appends other to the vector and returns a reference to the vector.

[since 5.11] QVector<T> &QVector::operator<<(T &&value)▲

This is an overloaded function.

This function was introduced in Qt 5.11.

QVector<T> &QVector::operator=(const QVector<T> &other)▲

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

[since 5.2] QVector<T> &QVector::operator=(QVector<T> &&other)▲

Move-assigns other to this QVector instance.

This function was introduced in Qt 5.2.

bool QVector::operator==(const QVector<T> &other) const▲

Returns true if other is equal to this vector; otherwise returns false.

Two vectors are considered equal if they contain the same values in the same order.

This function requires the value type to have an implementation of operator==().

T &QVector::operator[](int i)▲

Returns the item at index position i as a modifiable reference.

i must be a valid index position in the vector (i.e., 0 <= i < size()).

Note that using non-const operators can cause QVector to do a deep copy.

const T &QVector::operator[](int i) const▲

This is an overloaded function.

Same as at(i).

Related Non-Members▲

[since 5.6] uint qHash(const QVector<T> &key, uint seed = 0)▲

Returns the hash value for key, using seed to seed the calculation.

This function requires qHash() to be overloaded for the value type T.

This function was introduced in Qt 5.6.

[since 5.6] bool operator<(const QVector<T> &lhs, const QVector<T> &rhs)▲

Returns true if vector lhs is lexicographically less than rhs; otherwise returns false.

This function requires the value type to have an implementation of operator<().

This function was introduced in Qt 5.6.

QDataStream &operator<<(QDataStream &out, const QVector<T> &vector)▲

Writes the vector vector to stream out.

This function requires the value type to implement operator<<().

[since 5.6] bool operator<=(const QVector<T> &lhs, const QVector<T> &rhs)▲

Returns true if vector lhs is lexicographically less than or equal to rhs; otherwise returns false.

This function requires the value type to have an implementation of operator<().

This function was introduced in Qt 5.6.

[since 5.6] bool operator>(const QVector<T> &lhs, const QVector<T> &rhs)▲

Returns true if vector lhs is lexicographically greater than rhs; otherwise returns false.

This function requires the value type to have an implementation of operator<().

This function was introduced in Qt 5.6.

[since 5.6] bool operator>=(const QVector<T> &lhs, const QVector<T> &rhs)▲

Returns true if vector lhs is lexicographically greater than or equal to rhs; otherwise returns false.

This function requires the value type to have an implementation of operator<().

This function was introduced in Qt 5.6.

QDataStream &operator>>(QDataStream &in, QVector<T> &vector)▲

Reads a vector from stream in into vector.

This function requires the value type to implement operator>>().

QVector Class

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QVector Class▲

Detailed Description▲

More Information on Using Qt Containers▲

See Also▲

Member Type Documentation▲

QVector::ConstIterator▲

QVector::Iterator▲

QVector::const_iterator▲

See Also▲

QVector::const_pointer▲

QVector::const_reference▲

[since 5.6] QVector::const_reverse_iterator▲

See Also▲

QVector::difference_type▲

QVector::iterator▲

See Also▲

QVector::pointer▲

QVector::reference▲

[since 5.6] QVector::reverse_iterator▲

See Also▲

QVector::size_type▲

QVector::value_type▲

Member Function Documentation▲

void QVector::prepend(T &&value)▲

See Also▲

void QVector::insert(int i, T &&value)▲

See Also▲

QVector::iterator QVector::insert(QVector::iterator before, T &&value)▲

void QVector::push_front(T &&value)▲

QVector::QVector()▲

See Also▲

[explicit] QVector::QVector(int size)▲

See Also▲

QVector::QVector(int size, const T &value)▲

See Also▲

QVector::QVector(const QVector<T> &other)▲

See Also▲

[since 5.2] QVector::QVector(QVector<T> &&other)▲

[since 4.8] QVector::QVector(std::initializer_list<T> args)▲

QVector::~QVector()▲

void QVector::append(const T &value)▲

See Also▲

[since 5.6] void QVector::append(T &&value)▲

[since 5.5] void QVector::append(const QVector<T> &value)▲

See Also▲

const T &QVector::at(int i) const▲

See Also▲

QVector::reference QVector::back()▲

QVector::const_reference QVector::back() const▲

QVector::iterator QVector::begin()▲

See Also▲

QVector::const_iterator QVector::begin() const▲

int QVector::capacity() const▲

See Also▲

[since 5.0] QVector::const_iterator QVector::cbegin() const▲

See Also▲

[since 5.0] QVector::const_iterator QVector::cend() const▲

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void QVector::clear()▲

See Also▲

QVector::const_iterator QVector::constBegin() const▲

See Also▲

const T *QVector::constData() const▲

See Also▲

QVector::const_iterator QVector::constEnd() const▲

See Also▲

[since 5.6] const T &QVector::constFirst() const▲

See Also▲

[since 5.6] const T &QVector::constLast() const▲

See Also▲

bool QVector::contains(const T &value) const▲

See Also▲

int QVector::count(const T &value) const▲

See Also▲

int QVector::count() const▲

[since 5.6] QVector::const_reverse_iterator QVector::crbegin() const▲