QByteArrayView Class

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

Member Function Documentation

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

See also endsWith().

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

See also startsWith().

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 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 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 it is -2, at the next to last character and so on.

Returns -1 if no match is found.

See also indexOf() and contains().

[constexpr noexcept] QByteArrayView::QByteArrayView()

Constructs a null byte array view.

See also isNull().

[constexpr noexcept] QByteArrayView::QByteArrayView(std::nullptr_t)

Constructs a null byte array view.

See also isNull().

[constexpr] template <typename Byte, QByteArrayView::if_compatible_byte<Byte> = true> 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.

[constexpr] template <typename Byte, QByteArrayView::if_compatible_byte<Byte> = true> 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.

[constexpr noexcept] 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.

[noexcept] 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().

[constexpr noexcept] template <typename Container, QByteArrayView::if_compatible_container<Container> = true> 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 with elements of a compatible byte type.

See also Compatible Byte Types.

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

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.

See also fromArray.

[constexpr] 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().

[constexpr] char QByteArrayView::back() const

Returns the last byte in the byte array view.

This function is provided for STL compatibility.

See also front().

[constexpr noexcept] QByteArrayView::const_iterator QByteArrayView::begin() const

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

This function is provided for STL compatibility.

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

[constexpr noexcept] QByteArrayView::const_iterator QByteArrayView::cbegin() const

Same as begin().

This function is provided for STL compatibility.

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

[constexpr noexcept] QByteArrayView::const_iterator QByteArrayView::cend() const

Same as end().

This function is provided for STL compatibility.

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

[constexpr] void QByteArrayView::chop(qsizetype length)

Truncates this byte array view by length characters.

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

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

[constexpr] 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).

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

[noexcept, 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==().

[constexpr noexcept] QByteArrayView::const_pointer QByteArrayView::constData() const

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

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

[noexcept] 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().

[noexcept] 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().

[constexpr noexcept] QByteArrayView::const_reverse_iterator QByteArrayView::crbegin() const

Same as rbegin().

This function is provided for STL compatibility.

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

[constexpr noexcept] QByteArrayView::const_reverse_iterator QByteArrayView::crend() const

Same as rend().

This function is provided for STL compatibility.

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

[constexpr noexcept] QByteArrayView::const_pointer QByteArrayView::data() const

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

See also begin() and end().

[constexpr noexcept] 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().

[constexpr noexcept] QByteArrayView::const_iterator QByteArrayView::end() const

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

This function is provided for STL compatibility.

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

[constexpr] 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).

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

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

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.

[constexpr] char QByteArrayView::front() const

Returns the first byte in the byte array view.

This function is provided for STL compatibility.

See also back().

[constexpr noexcept] bool QByteArrayView::isEmpty() const

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

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

[constexpr noexcept] bool QByteArrayView::isNull() const

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

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

[noexcept, since 6.3] bool QByteArrayView::isValidUtf8() const

Returns true if this byte array view contains valid UTF-8 encoded data, or false otherwise.

This function was introduced in Qt 6.3.

[constexpr] QByteArrayView QByteArrayView::last(qsizetype n) const

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

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

[noexcept, 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().

[constexpr noexcept] qsizetype QByteArrayView::length() const

Same as size().

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

[constexpr noexcept] QByteArrayView::const_reverse_iterator QByteArrayView::rbegin() const

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

This function is provided for STL compatibility.

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

[constexpr noexcept] QByteArrayView::const_reverse_iterator QByteArrayView::rend() const

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

This function is provided for STL compatibility.

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

[constexpr noexcept] qsizetype QByteArrayView::size() const

Returns the number of bytes in this byte array view.

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

[constexpr] QByteArrayView QByteArrayView::sliced(qsizetype pos) const

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

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

[constexpr] 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.

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.

[since 6.3] double QByteArrayView::toDouble(bool *ok = nullptr) const

Returns this byte array view converted to a double value.

Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function ignores leading and trailing spacing characters.

This function was introduced in Qt 6.3.

[since 6.3] float QByteArrayView::toFloat(bool *ok = nullptr) const

Returns this byte array view converted to a float value.

Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

 QByteArrayView string("1234.56 Volt");
 bool ok;
 float a = str.toFloat(&ok);       // a == 0, ok == false
 a = string.first(7).toFloat(&ok); // a == 1234.56, ok == true

This function ignores leading and trailing whitespace.

This function was introduced in Qt 6.3.

[since 6.3] int QByteArrayView::toInt(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to an int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

 QByteArrayView str("FF");
 bool ok;
 int hex = str.toInt(&ok, 16);     // hex == 255, ok == true
 int dec = str.toInt(&ok, 10);     // dec == 0, ok == false

This function was introduced in Qt 6.3.

[since 6.3] long QByteArrayView::toLong(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to a long int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

 QByteArrayView str("FF");
 bool ok;
 long hex = str.toLong(&ok, 16);   // hex == 255, ok == true
 long dec = str.toLong(&ok, 10);   // dec == 0, ok == false

This function was introduced in Qt 6.3.

[since 6.3] qlonglong QByteArrayView::toLongLong(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to a long long using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function was introduced in Qt 6.3.

[since 6.3] short QByteArrayView::toShort(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to a short using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function was introduced in Qt 6.3.

[since 6.3] uint QByteArrayView::toUInt(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to an unsigned int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function was introduced in Qt 6.3.

[since 6.3] ulong QByteArrayView::toULong(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to an unsigned long int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function was introduced in Qt 6.3.

[since 6.3] qulonglong QByteArrayView::toULongLong(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to an unsigned long long using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function was introduced in Qt 6.3.

[since 6.3] ushort QByteArrayView::toUShort(bool *ok = nullptr, int base = 10) const

Returns this byte array view converted to an unsigned short using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: if the byte array view begins with "0x", the rest of it is read as hexadecimal (base 16); otherwise, if it begins with "0", the rest of it is read as octal (base 8); otherwise it is read as decimal.

Returns 0 if the conversion fails.

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

This function was introduced in Qt 6.3.

[noexcept, since 6.3] QByteArrayView QByteArrayView::trimmed() const

Returns a copy of this byte array view with spacing characters removed from the start and end.

The spacing characters are those for which the standard C++ isspace() function returns true in the C locale; these are the ASCII characters tabulation '\t', line feed '\n', carriage return '\r', vertical tabulation '\v', form feed '\f', and space ' '.

This function was introduced in Qt 6.3.

See also QChar::SpecialCharacter and Spacing Characters.

[constexpr] void QByteArrayView::truncate(qsizetype length)

Truncates this byte array view to length length.

Same as *this = first(length).

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

[constexpr noexcept, since 6.7] std::string_view QByteArrayView::operator std::string_view() const

Converts this QByteArrayView object to a std::string_view object. The returned view will have the same data pointer and length of this view.

This function was introduced in Qt 6.7.

[constexpr] 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().