QByteArrayView Class

     void myfun1(QByteArrayView bv);        // preferred
     void myfun2(const QByteArrayView &bv); // compiles and works, but slower

Member Function Documentation

Returns the index position of either the start of the last occurrence of the sequence of bytes viewed by bv or the last occurrence of byte ch, respectively, in this byte array view, searching backward from index position from. If from is -1, the search starts at the last character; if from is -2, at the next to last character and so on. Returns -1 if no match is found.

Note: When searching for a 0-length bv, the match at the end of the data is excluded from the search by a negative from, even though -1 is normally thought of as searching from the end of the view: the match at the end is after the last character, so it is excluded. To include such a final empty match, either give a positive value for from or omit the from parameter entirely.

See also indexOf() and contains().

Returns true if this byte array view contains an occurrence of the sequence of bytes viewed by bv or character ch, respectively; otherwise returns false.

See also indexOf() and lastIndexOf().

Returns the index position of either the start of the first occurrence of the sequence of bytes viewed by bv or the first occurrence of byte ch, respectively, in this byte array view, searching forward from index position from.Returns -1 if no match is found.

If from is -1, the search starts at the last character; if it is -2, at the next to last character and so on.

See also lastIndexOf() and contains().

Returns true if this byte array view ends with byte array view bv or character ch, respectively; otherwise returns false.

See also startsWith().

Returns true if this byte array view starts with byte array view bv or character ch, respectively; otherwise returns false.

See also endsWith().

template <size_t Size> QByteArrayView::QByteArrayView(const char (&)[Size] data = Size)

Constructs a byte array view on the char array data. The view covers the array until the first '\0' is encountered, or Size, whichever comes first. If you need the full array, use fromArray() instead.

data must remain valid for the lifetime of this byte array view object.

Note: This constructor is only available for char array literals. The reasoning behind that is for compatibility with C-libraries which predefine "large-enough" arrays, but only use some of the preallocated space. To support this in an intuitive way in an implicit constructor overload, we need to stop at the first char(0). This is logical for a char array, but not for a std::byte array.

See also fromArray.

template <typename Container, if_compatible_container<Container>> QByteArrayView::QByteArrayView(const Container &c)

Constructs a byte array view on the array-like container c. The length and data are set via std::size(c) and std::data(c) respectively.

The container's data must remain valid for the lifetime of this byte array view object.

This constructor participates in overload resolution if c is any contiguous container container with elements of a compatible byte type.

See also Compatible Byte Types.

QByteArrayView::QByteArrayView(const QByteArray &byteArray)

Constructs a byte array view on byteArray.

byteArray.data() must remain valid for the lifetime of this byte array view object.

The byte array view will be null if and only if byteArray.isNull().

template <typename Byte> QByteArrayView::QByteArrayView(const Byte *data)

Constructs a byte array view on data. The length is determined by scanning for the first Byte(0).

data must remain valid for the lifetime of this byte array view object.

Passing nullptr as data is safe and results in a null byte array view.

This constructor only participates in overload resolution if data is not an array and if Byte is a compatible byte type.

See also Compatible Byte Types.

template <typename Byte, if_compatible_byte<Byte>> QByteArrayView::QByteArrayView(const Byte *first, const Byte *last)

Constructs a byte array view on first with length (last - first).

The range [first,last) must remain valid for the lifetime of this QByteArrayView.

Passing \nullptr as first is safe if last is nullptr, too, and results in a null byte array view.

The behavior is undefined if last precedes first, or first is nullptr and last is not.

This constructor only participates in overload resolution if Byte is a compatible byte type.

See also Compatible Byte Types.

template <typename Byte, if_compatible_byte<Byte>> QByteArrayView::QByteArrayView(const Byte *data, qsizetype len)

Constructs a byte array view on data with length len.

The range [data,len) must remain valid for the lifetime of this QByteArrayView.

Passing nullptr as data is safe if len is 0, too, and results in a null byte array view.

The behavior is undefined if len is negative or, when positive, if data is nullptr.

This constructor only participates in overload resolution if Byte is a compatible byte type.

See also Compatible Byte Types.

QByteArrayView::QByteArrayView(std::nullptr_t)

Constructs a null byte array view.

See also isNull().

QByteArrayView::QByteArrayView()

Constructs a null byte array view.

See also isNull().

char QByteArrayView::at(qsizetype n) const

Returns the character at position n in this byte array view.

The behavior is undefined if n is negative or not less than size().

See also operator[](), front(), and back().

char QByteArrayView::back() const

Returns the last byte in the byte array.

This function is provided for STL compatibility.

Warning: Calling this function on an empty byte array view constitutes undefined behavior.

See also front().

QByteArrayView::const_iterator QByteArrayView::begin() const

Returns a const STL-style iterator pointing to the first byte in the byte array.

This function is provided for STL compatibility.

See also end(), cbegin(), rbegin(), and data().

QByteArrayView::const_iterator QByteArrayView::cbegin() const

Same as begin().

This function is provided for STL compatibility.

See also cend(), begin(), crbegin(), and data().

QByteArrayView::const_iterator QByteArrayView::cend() const

Same as end().

This function is provided for STL compatibility.

See also cbegin(), end(), and crend().

void QByteArrayView::chop(qsizetype length)

Truncates this byte array view by length characters.

Same as *this = first(size() - length).

Note: The behavior is undefined when length < 0 or length > size().

See also sliced(), first(), last(), chopped(), and truncate().

QByteArrayView QByteArrayView::chopped(qsizetype length) const

Returns a copy of this byte array view that omits its last length bytes. In other words, returns a byte array view of length size() - length starting at the beginning of this object.

Same as first(size() - length).

Note: The behavior is undefined when length < 0 or length > size().

See also first(), last(), sliced(), chop(), and truncate().

[since 6.2] int QByteArrayView::compare(QByteArrayView bv, Qt::CaseSensitivity cs = Qt::CaseSensitive) const

Returns an integer less than, equal to, or greater than zero depending on whether this QByteArrayView sorts before, at the same position as, or after the QByteArrayView bv. The comparison is performed according to case sensitivity cs.

This function was introduced in Qt 6.2.

See also operator==().

QByteArrayView::const_pointer QByteArrayView::constData() const

Returns a const char pointer to the first byte in the byte array.

Note: The character array represented by the return value is not guaranteed to be null-terminated. The returned pointer is only safe to use for accessing bytes at indices that are less than this byte array view's size().

See also data(), begin(), and end().

qsizetype QByteArrayView::count(QByteArrayView bv) const

Returns the number of (potentially overlapping) occurrences of the sequence of bytes viewed by bv in this byte array view.

See also contains() and indexOf().

qsizetype QByteArrayView::count(char ch) const

This is an overloaded function.

Returns the number of occurrences of byte ch in this byte array view.

See also contains() and indexOf().

QByteArrayView::const_reverse_iterator QByteArrayView::crbegin() const

Same as rbegin().

This function is provided for STL compatibility.

See also crend(), rbegin(), and cbegin().

QByteArrayView::const_reverse_iterator QByteArrayView::crend() const

Same as rend().

This function is provided for STL compatibility.

See also crbegin(), rend(), and cend().

QByteArrayView::const_pointer QByteArrayView::data() const

Returns a const char pointer to the first byte in the byte array.

Note: The character array represented by the return value is not guaranteed to be null-terminated. The returned pointer is only safe to use for accessing bytes at indices that are less than this byte array view's size().

See also begin() and end().

bool QByteArrayView::empty() const

Returns true if this byte array view is empty - that is, size() == 0.

This function is provided for STL compatibility.

See also isEmpty(), isNull(), and size().

QByteArrayView::const_iterator QByteArrayView::end() const

Returns a const STL-style iterator pointing just after the last byte in the byte array.

This function is provided for STL compatibility.

See also begin(), cend(), and rend().

QByteArrayView QByteArrayView::first(qsizetype n) const

Returns a byte array view that points to the first n bytes of this byte array view. Equivalent to sliced(0, n).

Note: The behavior is undefined when n < 0 or n > size().

See also last(), startsWith(), chopped(), chop(), and truncate().

[static] template <typename Byte, size_t Size> QByteArrayView QByteArrayView::fromArray(const Byte (&)[Size] data = Size)

Constructs a byte array view on the array literal data. The view covers the full array. That includes the trailing null-terminator of char array literals. If you don't want the null-terminator included in the view, you can chop() it off when you are certain it is at the end. Alternatively you can use the constructor overload taking a char array literal which will create a view up to, but not including, the first null-terminator in the data.

This function will work with any array literal of a compatible byte type.

See also Compatible Byte Types and QByteArrayView.

char QByteArrayView::front() const

Returns the first byte in the byte array.

This function is provided for STL compatibility.

Warning: Calling this function on an empty byte array view constitutes undefined behavior.

See also back().

bool QByteArrayView::isEmpty() const

Returns true if this byte array view is empty - that is, size() == 0.

See also empty(), isNull(), and size().

bool QByteArrayView::isNull() const

Returns true if this byte array view is null - that is, data() == nullptr.

See also empty(), isEmpty(), and size().

QByteArrayView QByteArrayView::last(qsizetype n) const

Returns a byte array view that points to the last n bytes of this byte array view.

Note: The behavior is undefined when n < 0 or n > size().

See also first(), endsWith(), chopped(), chop(), and truncate().

[since 6.2] qsizetype QByteArrayView::lastIndexOf(QByteArrayView bv) const

This is an overloaded function.

Returns the index position of the start of the last occurrence of the sequence of bytes viewed by bv in this byte array view, searching backward from the end of this byte array view. Returns -1 if no match is found.

This function was introduced in Qt 6.2.

See also indexOf() and contains().

qsizetype QByteArrayView::length() const

Same as size().

See also empty(), isEmpty(), isNull(), and size().

QByteArrayView::const_reverse_iterator QByteArrayView::rbegin() const

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

This function is provided for STL compatibility.

See also rend(), crbegin(), and begin().

QByteArrayView::const_reverse_iterator QByteArrayView::rend() const

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

This function is provided for STL compatibility.

See also rbegin(), crend(), and end().

qsizetype QByteArrayView::size() const

Returns the number of bytes in this byte array view.

See also empty(), isEmpty(), and isNull().

QByteArrayView QByteArrayView::sliced(qsizetype pos) const

Returns a byte array view starting at position pos in this object, and extending to its end.

Note: The behavior is undefined when pos < 0 or pos > size().

See also first(), last(), chopped(), chop(), and truncate().

QByteArrayView QByteArrayView::sliced(qsizetype pos, qsizetype n) const

Returns a byte array view that points to n bytes of this byte array view, starting at position pos.

Note: The behavior is undefined when pos < 0, n < 0, or pos + n > size().

See also first(), last(), chopped(), chop(), and truncate().

QByteArray QByteArrayView::toByteArray() const

Returns a deep copy of this byte array view's data as a QByteArray.

The return value will be a null QByteArray if and only if this byte array view is null.

Warning: QByteArrayView can store data with more than 2³¹ bytes while QByteArray cannot. Calling this function on a byte array view for which size() returns a value greater than INT_MAX / 2 constitutes undefined behavior.

void QByteArrayView::truncate(qsizetype length)

Truncates this byte array view to length length.

Same as *this = first(length).

Note: The behavior is undefined when length < 0 or length > size().

See also first(), last(), sliced(), chopped(), and chop().

char QByteArrayView::operator[](qsizetype n) const

Returns the character at position n in this byte array view.

The behavior is undefined if n is negative or not less than size().

See also at(), front(), and back().