QAnyStringView 类提供 Latin-1、UTF-8 或 UTF-16 的统一字符串视图，采用只读子集的 QString API. 更多...
| 头： | #include <QAnyStringView> |
| CMake: |
find_package(Qt6 COMPONENTS Core REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Core) |
| qmake: | QT += core |
| Since: | Qt 6.0 |
注意： 此类的所有函数 可重入 .
| difference_type | |
| size_type |
| QAnyStringView (const QString & str ) | |
| QAnyStringView (const QByteArray & str ) | |
| QAnyStringView (const Char * str ) | |
| QAnyStringView (const Char (&)[N] string = N) | |
| QAnyStringView (const Char * first , const Char * last ) | |
| QAnyStringView (const Char * str , qsizetype len ) | |
| QAnyStringView (std::nullptr_t) | |
| QAnyStringView () | |
| QChar | back () const |
| const void * | data () const |
| bool | empty () const |
| QChar | front () const |
| bool | isEmpty () const |
| bool | isNull () const |
| qsizetype | length () const |
| qsizetype | size () const |
| qsizetype | size_bytes () const |
| QString | toString () const |
| int | compare (QAnyStringView lhs , QAnyStringView rhs , Qt::CaseSensitivity cs = Qt::CaseSensitive) |
| bool | operator!= (QAnyStringView lhs , QAnyStringView rhs ) |
| bool | operator< (QAnyStringView lhs , QAnyStringView rhs ) |
| bool | operator<= (QAnyStringView lhs , QAnyStringView rhs ) |
| bool | operator== (QAnyStringView lhs , QAnyStringView rhs ) |
| bool | operator> (QAnyStringView lhs , QAnyStringView rhs ) |
| bool | operator>= (QAnyStringView lhs , QAnyStringView rhs ) |
A QAnyStringView references a contiguous portion of a string it does not own. It acts as an interface type to all kinds of strings, without the need to construct a QString 首先。
不像 QStringView and QUtf8StringView , QAnyStringView can hold strings of any of the following encodings: UTF-8, UTF-16, and Latin-1. The latter is supported to keep old source working efficiently. It is expected that by Qt 7, the Latin-1 support will be removed.
The string may be represented as an array (or an array-compatible data-structure such as
QString
, std::basic_string, etc.) of
char
,
char8_t
,
QChar
,
ushort
,
char16_t
or (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
QAnyStringView is designed as an interface type; its main use-case is as a function parameter type. When QAnyStringViews are used as automatic variables or data members, care must be taken to ensure that the referenced string data (for example, owned by a QString ) outlives the QAnyStringView on all code paths, lest the string view ends up referencing deleted data.
When used as an interface type, QAnyStringView allows a single function to accept a wide variety of string data sources. One function accepting QAnyStringView thus replaces five function overloads (taking
QString
,
(const QChar*, int)
,
QUtf8StringView
,
QLatin1String
(but see above), and
QChar
), while at the same time enabling even more string data sources to be passed to the function, such as
u8"Hello World"
，
char8_t
字符串文字。
Like elsewhere in Qt, QAnyStringView assumes
char
data is encoded in UTF-8, unless it is presented as a
QLatin1String
.
QAnyStringViews should be passed by value, not by reference-to-const:
void myfun1(QAnyStringView sv); // preferred
void myfun2(const QAnyStringView &sv); // compiles and works, but slower
QAnyStringView can also be used as the return value of a function, but this is not recommended. QUtf8StringView or QStringView are better suited as function return values. If you call a function returning QAnyStringView, take extra care to not keep the QAnyStringView around longer than the function promises to keep the referenced string data alive. If in doubt, obtain a strong reference to the data by calling toString () to convert the QAnyStringView into a QString .
QAnyStringView is a Literal Type .
QAnyStringView 接受各种字符类型的字符串：
char
(有符号和无符号两者)
char8_t
(仅 C++20)
char16_t
wchar_t
(在此是 16 位类型，如 Windows)
ushort
QChar
The 8-bit character types are interpreted as UTF-8 data (except when presented as a QLatin1String ) while the 16-bit character types are interpreted as UTF-16 data in host byte order (the same as QString ).
All sizes and positions in QAnyStringView functions are in the encoding's code points (that is, UTF-16 surrogate pairs count as two for the purposes of these functions, the same as in QString , and UTF-8 multibyte sequences count as two, three or four, depending on their length).
另请参阅 QUtf8StringView and QStringView .
别名化的
std::ptrdiff_t
. Provided for compatibility with the STL.
Alias for qsizetype. Provided for compatibility with the STL.
Constructs a string view on str .
str.data()
must remain valid for the lifetime of this string view object.
The string view will be null if and only if
str.isNull()
.
Constructs a string view on str . The data in str is interpreted as UTF-8.
str.data()
must remain valid for the lifetime of this string view object.
The string view will be null if and only if
str.isNull()
.
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.
传递
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.
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
Char
is a compatible character type.
另请参阅 兼容字符类型 .
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.
传递
\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
，或
first
is
nullptr
and
last
is not.
This constructor only participates in overload resolution if
Char
is a compatible character type.
Constructs a string view on str with length len .
The range
[str,len)
must remain valid for the lifetime of this string view object.
传递
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.
Constructs a null string view.
另请参阅 isNull ().
Constructs a null string view.
另请参阅 isNull ().
Returns the last character in the string.
This function is provided for STL compatibility.
警告： Calling this function on an empty string view constitutes undefined behavior.
[static]
int
QAnyStringView::
compare
(
QAnyStringView
lhs
,
QAnyStringView
rhs
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive)
Returns an integer that compares to zero as lhs compares to rhs .
若 cs is Qt::CaseSensitive (the default), the comparison is case sensitive; otherwise the comparison is case-insensitive.
另请参阅 operator== (), operator< ()，和 operator> ().
Returns a const pointer to the first character in the string.
注意： The character array represented by the return value is not null-terminated.
另请参阅 size_bytes ().
Returns whether this string view is empty - that is, whether
size() == 0
.
This function is provided for STL compatibility.
另请参阅 isEmpty (), isNull ()，和 size ().
Returns the first character in the string.
This function is provided for STL compatibility.
警告： Calling this function on an empty string view constitutes undefined behavior.
Returns whether this string view is empty - that is, whether
size() == 0
.
This function is provided for compatibility with other Qt containers.
另请参阅 empty (), isNull ()，和 size ().
Returns whether this string view is null - that is, whether
data() == nullptr
.
This functions is provided for compatibility with other Qt containers.
另请参阅 empty (), isEmpty ()，和 size ().
如同 size ().
This function is provided for compatibility with other Qt containers.
另请参阅 size ().
Returns the size of this string view, in the encoding's code points.
另请参阅 empty (), isEmpty (), isNull (), size_bytes ()，和 大小和子字符串 .
Returns the size of this string view, but in bytes, not code-points.
You can use this function together with data () for hashing or serialization.
This function is provided for STL compatibility.
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.
Operators that compare lhs to rhs .
另请参阅 compare ().