QUtf8StringView Class

     void myfun1(QUtf8StringView sv);        // preferred
     void myfun2(const QUtf8StringView &sv); // compiles and works, but slower

Member Function Documentation

Compares this string view with str and returns a negative integer if this string view is less than str, a positive integer if it is greater than str, and zero if they are equal.

If cs is Qt::CaseSensitive (the default), the comparison is case-sensitive; otherwise the comparison is case-insensitive.

This function was introduced in Qt 6.5.

[constexpr noexcept] QUtf8StringView::QUtf8StringView()

Constructs a null string view.

See also isNull().

[constexpr noexcept] template <typename Char, size_t N> QUtf8StringView::QUtf8StringView(const Char (&)[N] string)

Constructs a string view on the character string literal string. The view covers the array until the first Char(0) is encountered, or N, whichever comes first. If you need the full array, use fromArray() instead.

string must remain valid for the lifetime of this string view object.

This constructor only participates in overload resolution if string is an actual array and if Char is a compatible character type. The compatible character types are: char8_t, char, signed char and unsigned char.

See also fromArray().

[constexpr noexcept] template <typename Char> QUtf8StringView::QUtf8StringView(const Char *str)

Constructs a string view on str. The length is determined by scanning for the first Char(0).

str must remain valid for the lifetime of this string view object.

Passing nullptr as str is safe and results in a null string view.

This constructor only participates in overload resolution if str is not an array and if Char is a compatible character type. The compatible character types are: char8_t, char, signed char and unsigned char.

[constexpr noexcept] template <typename Container, QUtf8StringView::if_compatible_container<Container> = true> QUtf8StringView::QUtf8StringView(const Container &str)

Constructs a string view on str. The length is taken from std::size(str).

std::data(str) must remain valid for the lifetime of this string view object.

This constructor only participates in overload resolution if Container is a container with a compatible character type as value_type. The compatible character types are: char8_t, char, signed char and unsigned char.

The string view will be empty if and only if std::size(str) == 0. It is unspecified whether this constructor can result in a null string view (std::data(str) would have to return nullptr for this).

See also isNull() and isEmpty().

[constexpr noexcept] QUtf8StringView::QUtf8StringView(std::nullptr_t)

Constructs a null string view.

See also isNull().

[constexpr] template <typename Char, QUtf8StringView::if_compatible_char<Char> = true> QUtf8StringView::QUtf8StringView(const Char *first, const Char *last)

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

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

Passing \nullptr as first is safe if last is nullptr, too, and results in a null string 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 Char is a compatible character type. The compatible character types are: char8_t, char, signed char and unsigned char.

[constexpr] template <typename Char, QUtf8StringView::if_compatible_char<Char> = true> QUtf8StringView::QUtf8StringView(const Char *str, qsizetype len)

Constructs a string view on str with length len.

The range [str,len) must remain valid for the lifetime of this string view object.

Passing nullptr as str is safe if len is 0, too, and results in a null string view.

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

This constructor only participates in overload resolution if Char is a compatible character type. The compatible character types are: char8_t, char, signed char and unsigned char.

[constexpr] QUtf8StringView::storage_type QUtf8StringView::at(qsizetype n) const

Returns the code point at position n in this string view.

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

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

[constexpr] QUtf8StringView::storage_type QUtf8StringView::back() const

Returns the last code point in the string view. Same as last().

This function is provided for STL compatibility.

See also front().

[noexcept] QUtf8StringView::const_iterator QUtf8StringView::begin() const

Returns a const STL-style iterator pointing to the first code point in the string view.

This function is provided for STL compatibility.

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

[noexcept] QUtf8StringView::const_iterator QUtf8StringView::cbegin() const

Same as begin().

This function is provided for STL compatibility.

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

[noexcept] QUtf8StringView::const_iterator QUtf8StringView::cend() const

Same as end().

This function is provided for STL compatibility.

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

[constexpr] void QUtf8StringView::chop(qsizetype n)

Truncates this string view by n code points.

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

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

[constexpr] QUtf8StringView QUtf8StringView::chopped(qsizetype n) const

Returns the substring of length size() - n starting at the beginning of this object.

Same as first(size() - n).

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

[noexcept] QUtf8StringView::const_reverse_iterator QUtf8StringView::crbegin() const

Same as rbegin().

This function is provided for STL compatibility.

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

[noexcept] QUtf8StringView::const_reverse_iterator QUtf8StringView::crend() const

Same as rend().

This function is provided for STL compatibility.

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

[constexpr noexcept] QUtf8StringView::const_pointer QUtf8StringView::data() const

Returns a const pointer to the first code point in the string view.

See also begin(), end(), and utf8().

[constexpr noexcept] bool QUtf8StringView::empty() const

Returns whether this string view is empty - that is, whether size() == 0.

This function is provided for STL compatibility.

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

[noexcept] QUtf8StringView::const_iterator QUtf8StringView::end() const

Returns a const STL-style iterator pointing to the imaginary code point after the last code point in the list.

This function is provided for STL compatibility.

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

[constexpr] QUtf8StringView QUtf8StringView::first(qsizetype n) const

Returns a string view that contains the first n code points of this string view.

See also last(), sliced(), chopped(), chop(), truncate(), and slice().

[static constexpr noexcept] template <typename Char, size_t Size, QUtf8StringView::if_compatible_char<Char> = true> QUtf8StringView QUtf8StringView::fromArray(const Char (&)[Size] string)

Constructs a string view on the full character string literal string, including any trailing Char(0). If you don't want the null-terminator included in the view then you can chop() it off when you are certain it is at the end. Alternatively you can use the constructor overload taking an array literal which will create a view up to, but not including, the first null-terminator in the data.

string must remain valid for the lifetime of this string view object.

This function will work with any array literal if Char is a compatible character type. The compatible character types are: char8_t, char, signed char and unsigned char.

[constexpr] QUtf8StringView::storage_type QUtf8StringView::front() const

Returns the first code point in the string view. Same as first().

This function is provided for STL compatibility.

See also back().

[constexpr noexcept] bool QUtf8StringView::isEmpty() const

Returns whether this string view is empty - that is, whether size() == 0.

This function is provided for compatibility with other Qt containers.

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

[constexpr noexcept] bool QUtf8StringView::isNull() const

Returns whether this string view is null - that is, whether data() == nullptr.

This functions is provided for compatibility with other Qt containers.

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

[noexcept, since 6.3] bool QUtf8StringView::isValidUtf8() const

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

This function was introduced in Qt 6.3.

[constexpr] QUtf8StringView QUtf8StringView::last(qsizetype n) const

Returns a string view that contains the last n code points of this string view.

See also first(), sliced(), chopped(), chop(), truncate(), and slice().

[constexpr noexcept] qsizetype QUtf8StringView::length() const

Same as size().

This function is provided for compatibility with other Qt containers.

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

[static constexpr noexcept, since 6.8] qsizetype QUtf8StringView::maxSize()

It returns the maximum number of elements that the view can theoretically represent. In practice, the number can be much smaller, limited by the amount of memory available to the system.

This function was introduced in Qt 6.8.

[constexpr noexcept, since 6.8] qsizetype QUtf8StringView::max_size() const

This function is provided for STL compatibility.

Returns maxSize().

This function was introduced in Qt 6.8.

[noexcept] QUtf8StringView::const_reverse_iterator QUtf8StringView::rbegin() const

Returns a const STL-style reverse iterator pointing to the first code point in the string view, in reverse order.

This function is provided for STL compatibility.

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

[noexcept] QUtf8StringView::const_reverse_iterator QUtf8StringView::rend() const

Returns a STL-style reverse iterator pointing to one past the last code point in the string view, in reverse order.

This function is provided for STL compatibility.

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

[constexpr noexcept] qsizetype QUtf8StringView::size() const

Returns the size of this string view, in UTF-8 code points (that is, multi-byte sequences count as more than one for the purposes of this function, the same as surrogate pairs in QString and QStringView).

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

[constexpr, since 6.8] QUtf8StringView &QUtf8StringView::slice(qsizetype pos, qsizetype n)

Modifies this string view to start at position pos, extending for n code points.

This function was introduced in Qt 6.8.

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

[constexpr, since 6.8] QUtf8StringView &QUtf8StringView::slice(qsizetype pos)

This is an overloaded function.

Modifies this string view to start at position pos, extending to its end.

This function was introduced in Qt 6.8.

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

[constexpr] QUtf8StringView QUtf8StringView::sliced(qsizetype pos) const

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

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

[constexpr] QUtf8StringView QUtf8StringView::sliced(qsizetype pos, qsizetype n) const

Returns a string view containing n code points of this string view, starting at position pos.

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

QString QUtf8StringView::toString() const

Returns a deep copy of this string view's data as a QString.

The return value will be a null QString if and only if this string view is null.

[constexpr] void QUtf8StringView::truncate(qsizetype n)

Truncates this string view to n code points.

Same as *this = first(n).

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

[noexcept] const char8_t *QUtf8StringView::utf8() const

Returns a const pointer to the first code point in the string view.

The result is returned as a const char8_t*, so this function is only available when compiling in C++20 mode.

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

[noexcept, since 6.7] std::basic_string_view<QUtf8StringView::storage_type> QUtf8StringView::operator std::basic_string_view<QUtf8StringView::storage_type>() const

Converts this QUtf8StringView object to a std::basic_string_view object. The returned view will have the same data pointer and length of this view. The character type of the returned view will be storage_type.

This function was introduced in Qt 6.7.

[constexpr] QUtf8StringView::storage_type QUtf8StringView::operator[](qsizetype n) const

Returns the code point at position n in this string view.

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

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