QStringView 类提供 UTF-16 字符串统一视图，采用只读子集的 QString API. 更多...
| 头： | #include <QStringView> |
| CMake: |
find_package(Qt6 COMPONENTS Core REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Core) |
| qmake: | QT += core |
| Since: | Qt 5.10 |
注意： 此类的所有函数 可重入 .
| const_iterator | |
| const_pointer | |
| const_reference | |
| const_reverse_iterator | |
| difference_type | |
| iterator | |
| pointer | |
| reference | |
| reverse_iterator | |
| size_type | |
| storage_type | |
| value_type |
| QStringView (const Container & str ) | |
| QStringView (const QString & str ) | |
| QStringView (const Char * str ) | |
| QStringView (const Char (&)[N] string = N) | |
| QStringView (const Char * first , const Char * last ) | |
| QStringView (const Char * str , qsizetype len ) | |
| QStringView (std::nullptr_t) | |
| QStringView () | |
| QString | arg (Args &&... args ) const |
| QChar | at (qsizetype n ) const |
| QChar | back () const |
| QStringView::const_iterator | begin () const |
| QStringView::const_iterator | cbegin () const |
| QStringView::const_iterator | cend () const |
| void | chop (qsizetype length ) |
| QStringView | chopped (qsizetype length ) const |
| int | compare (QStringView str , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| int | compare (QLatin1String l1 , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| int | compare (QChar ch ) const |
| int | compare (QChar ch , Qt::CaseSensitivity cs ) const |
| QStringView::const_iterator | constBegin () const |
| QStringView::const_pointer | constData () const |
| QStringView::const_iterator | constEnd () const |
| bool | contains (QChar c , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | contains (QStringView str , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | contains (QLatin1String l1 , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | contains (const QRegularExpression & re , QRegularExpressionMatch * rmatch = nullptr) const |
| qsizetype | count (const QRegularExpression & re ) const |
| qsizetype | count (QChar ch , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | count (QStringView str , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| QStringView::const_reverse_iterator | crbegin () const |
| QStringView::const_reverse_iterator | crend () const |
| QStringView::const_pointer | data () const |
| bool | empty () const |
| QStringView::const_iterator | end () const |
| bool | endsWith (QStringView str , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | endsWith (QLatin1String l1 , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | endsWith (QChar ch ) const |
| bool | endsWith (QChar ch , Qt::CaseSensitivity cs ) const |
| QStringView | first (qsizetype n ) const |
| QChar | first () const |
| QChar | front () const |
| qsizetype | indexOf (QChar c , qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | indexOf (QStringView str , qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | indexOf (QLatin1String l1 , qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | indexOf (const QRegularExpression & re , qsizetype from = 0, QRegularExpressionMatch * rmatch = nullptr) const |
| bool | isEmpty () const |
| bool | isNull () const |
| bool | isRightToLeft () const |
| bool | isValidUtf16 () const |
| QStringView | last (qsizetype n ) const |
| QChar | last () const |
| qsizetype | lastIndexOf (QChar c , qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | lastIndexOf (QStringView str , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | lastIndexOf (QStringView str , qsizetype from , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | lastIndexOf (QLatin1String l1 , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | lastIndexOf (QLatin1String l1 , qsizetype from , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| qsizetype | lastIndexOf (const QRegularExpression & re , QRegularExpressionMatch * rmatch = nullptr) const |
| qsizetype | lastIndexOf (const QRegularExpression & re , qsizetype from , QRegularExpressionMatch * rmatch = nullptr) const |
| qsizetype | length () const |
| QStringView::const_reverse_iterator | rbegin () const |
| QStringView::const_reverse_iterator | rend () const |
| qsizetype | size () const |
| QStringView | sliced (qsizetype pos , qsizetype n ) const |
| QStringView | sliced (qsizetype pos ) const |
| QList<QStringView> | split (QStringView sep , Qt::SplitBehavior behavior = Qt::KeepEmptyParts, Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| QList<QStringView> | split (QChar sep , Qt::SplitBehavior behavior = Qt::KeepEmptyParts, Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| QList<QStringView> | split (const QRegularExpression & re , Qt::SplitBehavior behavior = Qt::KeepEmptyParts) const |
| bool | startsWith (QStringView str , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | startsWith (QLatin1String l1 , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| bool | startsWith (QChar ch ) const |
| bool | startsWith (QChar ch , Qt::CaseSensitivity cs ) const |
| CFStringRef | toCFString () const |
| double | toDouble (bool * ok = nullptr) const |
| float | toFloat (bool * ok = nullptr) const |
| int | toInt (bool * ok = nullptr, int base = 10) const |
| QByteArray | toLatin1 () const |
| QByteArray | toLocal8Bit () const |
| long | toLong (bool * ok = nullptr, int base = 10) const |
| qlonglong | toLongLong (bool * ok = nullptr, int base = 10) const |
| NSString * | toNSString () const |
| short | toShort (bool * ok = nullptr, int base = 10) const |
| QString | toString () const |
| uint | toUInt (bool * ok = nullptr, int base = 10) const |
| ulong | toULong (bool * ok = nullptr, int base = 10) const |
| qulonglong | toULongLong (bool * ok = nullptr, int base = 10) const |
| ushort | toUShort (bool * ok = nullptr, int base = 10) const |
| QList<uint> | toUcs4 () const |
| QByteArray | toUtf8 () const |
| qsizetype | toWCharArray (wchar_t * array ) const |
| decltype(qTokenize(*this, std::forward<Needle>(needle), flags...)) | tokenize (Needle && sep , Flags... flags ) const |
| QStringView | trimmed () const |
| void | truncate (qsizetype length ) |
| const QStringView::storage_type * | utf16 () const |
| QChar | operator[] (qsizetype n ) const |
| QStringView | fromArray (const Char (&)[Size] string = Size) |
| size_t | qHash (QStringView key , size_t seed = 0) |
| bool | operator!= (QStringView lhs , QStringView rhs ) |
| bool | operator< (QStringView lhs , QStringView rhs ) |
| bool | operator<= (QStringView lhs , QStringView rhs ) |
| bool | operator== (QStringView lhs , QStringView rhs ) |
| bool | operator> (QStringView lhs , QStringView rhs ) |
| bool | operator>= (QStringView lhs , QStringView rhs ) |
A QStringView references a contiguous portion of a UTF-16 string it does not own. It acts as an interface type to all kinds of UTF-16 string, without the need to construct a QString 首先。
The UTF-16 string may be represented as an array (or an array-compatible data-structure such as
QString
, std::basic_string, etc.) of
QChar
,
ushort
,
char16_t
or (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
QStringView is designed as an interface type; its main use-case is as a function parameter type. When QStringViews 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 QStringView on all code paths, lest the string view ends up referencing deleted data.
When used as an interface type, QStringView allows a single function to accept a wide variety of UTF-16 string data sources. One function accepting QStringView thus replaces three function overloads (taking
QString
and
(const QChar*, int)
), while at the same time enabling even more string data sources to be passed to the function, such as
u"Hello World"
，
char16_t
字符串文字。
QStringViews should be passed by value, not by reference-to-const:
void myfun1(QStringView sv); // preferred
void myfun2(const QStringView &sv); // compiles and works, but slower
If you want to give your users maximum freedom in what strings they can pass to your function, accompany the QStringView overload with overloads for
void fun(QChar ch) { fun(QStringView(&ch, 1)); }
even though, for technical reasons, QStringView cannot provide a QChar constructor by itself.
QStringView can also be used as the return value of a function. If you call a function returning QStringView, take extra care to not keep the QStringView 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 QStringView into a QString .
QStringView is a
Literal Type
, but since it stores data as
char16_t
, iteration is not
constexpr
(casts from
const char16_t*
to
const QChar*
, which is not allowed in
constexpr
functions). You can use an indexed loop and/or
utf16
() 在
constexpr
contexts instead.
另请参阅 QString .
此 typedef 提供 STL 样式 const 迭代器为 QStringView .
另请参阅 iterator and const_reverse_iterator .
别名化的
value_type *
. Provided for compatibility with the STL.
别名化的
value_type &
. Provided for compatibility with the STL.
This typedef provides an STL-style const reverse iterator for QStringView .
另请参阅 reverse_iterator and const_iterator .
别名化的
std::ptrdiff_t
. Provided for compatibility with the STL.
此 typedef 提供 STL 样式 const 迭代器为 QStringView .
QStringView does not support mutable iterators, so this is the same as const_iterator .
另请参阅 const_iterator and reverse_iterator .
别名化的
value_type *
. Provided for compatibility with the STL.
QStringView does not support mutable pointers, so this is the same as const_pointer .
别名化的
value_type &
. Provided for compatibility with the STL.
QStringView does not support mutable references, so this is the same as const_reference .
This typedef provides an STL-style const reverse iterator for QStringView .
QStringView does not support mutable reverse iterators, so this is the same as const_reverse_iterator .
另请参阅 const_reverse_iterator and iterator .
Alias for qsizetype. Provided for compatibility with the STL.
别名化的
char16_t
.
别名化的
const QChar
. Provided for compatibility with the STL.
[since 6.0]
template <typename Needle, typename Flags>
decltype
(
qTokenize
(*
this
,
std::forward
<
Needle
>(
needle
),
flags
...)) QStringView::
tokenize
(
Needle
&&
sep
,
Flags
...
flags
) const
Splits the string into substring views wherever sep occurs, and returns a lazy sequence of those strings.
相当于
return QStringTokenizer{std::forward<Needle>(sep), flags...};
except it works without C++17 Class Template Argument Deduction (CTAD) enabled in the compiler.
见 QStringTokenizer for how sep and flags interact to form the result.
注意： While this function returns QStringTokenizer , you should never, ever, name its template arguments explicitly. If you can use C++17 Class Template Argument Deduction (CTAD), you may write
QStringTokenizer result = sv.tokenize(sep);
(without template arguments). If you can't use C++17 CTAD, you must store the return value only in
auto
variables:
auto result = sv.tokenize(sep);
This is because the template arguments of QStringTokenizer have a very subtle dependency on the specific tokenize () overload from which they are returned, and they don't usually correspond to the type used for the separator.
该函数在 Qt 6.0 引入。
另请参阅 QStringTokenizer and qTokenize ().
[since 6.2]
qsizetype
QStringView::
lastIndexOf
(
QLatin1String
l1
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 6.2]
qsizetype
QStringView::
lastIndexOf
(
QStringView
str
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
此函数重载 lastIndexOf ().
Returns the index position of the last occurrence of the string view str or Latin-1 string l1 , respectively, in this string view, searching backward from the last character of this string view. Returns -1 if str 找不到。
若 cs is Qt::CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 6.2 引入。
另请参阅 QString::lastIndexOf ().
[since 5.14]
qsizetype
QStringView::
lastIndexOf
(
QChar
c
,
qsizetype
from
= -1,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 5.14]
qsizetype
QStringView::
lastIndexOf
(
QLatin1String
l1
,
qsizetype
from
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 5.14]
qsizetype
QStringView::
lastIndexOf
(
QStringView
str
,
qsizetype
from
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
Returns the index position of the last occurrence of the string view str , Latin-1 string l1 , or character ch , respectively, in this string view, searching backward from index position from 。若 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 str 找不到。
若 cs is Qt::CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
注意：
When searching for a 0-length
str
or
l1
, 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 string 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.
该函数在 Qt 5.14 引入。
另请参阅 QString::lastIndexOf ().
[since 5.14]
bool
QStringView::
contains
(
QChar
c
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 5.14]
bool
QStringView::
contains
(
QLatin1String
l1
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 5.14]
bool
QStringView::
contains
(
QStringView
str
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
返回
true
if this string-view contains an occurrence of the string-view
str
, Latin-1 string
l1
, or character
ch
；否则返回
false
.
若 cs is Qt::CaseSensitive (the default), the search is case-sensitive; otherwise the search is case-insensitive.
该函数在 Qt 5.14 引入。
另请参阅 indexOf ().
[since 5.14]
qsizetype
QStringView::
indexOf
(
QChar
c
,
qsizetype
from
= 0,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 5.14]
qsizetype
QStringView::
indexOf
(
QLatin1String
l1
,
qsizetype
from
= 0,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 5.14]
qsizetype
QStringView::
indexOf
(
QStringView
str
,
qsizetype
from
= 0,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
Returns the index position of the first occurrence of the string-view str , Latin-1 string l1 , or character ch , respectively, in this string-view, searching forward from index position from . Returns -1 if str 找不到。
若 cs is Qt::CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
若 from is -1, the search starts at the last character; if it is -2, at the next to last character and so on.
该函数在 Qt 5.14 引入。
另请参阅 QString::indexOf ().
返回
true
if this string-view ends with string-view
str
, Latin-1 string
l1
, or character
ch
, respectively; otherwise returns
false
.
若 cs is Qt::CaseSensitive (the default), the search is case-sensitive; otherwise the search is case-insensitive.
另请参阅 startsWith ().
返回
true
if this string-view starts with string-view
str
, Latin-1 string
l1
, or character
ch
, respectively; otherwise returns
false
.
若 cs is Qt::CaseSensitive (the default), the search is case-sensitive; otherwise the search is case-insensitive.
另请参阅 endsWith ().
[since 5.15]
int
QStringView::
compare
(
QChar
ch
) const
[since 5.15]
int
QStringView::
compare
(
QChar
ch
,
Qt::CaseSensitivity
cs
) const
[since 5.15]
int
QStringView::
compare
(
QLatin1String
l1
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
Returns an integer that compares to zero as this string-view compares to the Latin-1 string l1 , or character ch ，分别。
若 cs is Qt::CaseSensitive (the default), the comparison is case sensitive; otherwise the comparison is case-insensitive.
该函数在 Qt 5.15 引入。
另请参阅 operator== (), operator< ()，和 operator> ().
[since 5.14]
template <typename Args>
QString
QStringView::
arg
(
Args
&&...
args
) const
Replaces occurrences of
%N
in this string with the corresponding argument from
args
. The arguments are not positional: the first of the
args
replaces the
%N
with the lowest
N
(all of them), the second of the
args
%N
with the next-lowest
N
etc.
Args
can consist of anything that implicitly converts to
QString
,
QStringView
or
QLatin1String
.
In addition, the following types are also supported: QChar , QLatin1Char .
该函数在 Qt 5.14 引入。
另请参阅 QString::arg ().
[since 6.0]
QList
<
QStringView
> QStringView::
split
(
QChar
sep
,
Qt::SplitBehavior
behavior
= Qt::KeepEmptyParts,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
[since 6.0]
QList
<
QStringView
> QStringView::
split
(
QStringView
sep
,
Qt::SplitBehavior
behavior
= Qt::KeepEmptyParts,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
Splits the string into substring views wherever sep occurs, and returns the list of those string views.
见 QString::split () for how sep , behavior and cs interact to form the result.
注意： All views are valid as long as this string is. Destroying this string will cause all views to be dangling pointers.
该函数在 Qt 6.0 引入。
Constructs a string view on
str
. The length is taken from
str.size()
.
str.data()
must remain valid for the lifetime of this string view object.
This constructor only participates in overload resolution if
StdBasicString
is an instantiation of
std::basic_string
with a compatible character type. The compatible character types are:
QChar
,
ushort
,
char16_t
and (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
The string view will be empty if and only if
str.empty()
. It is unspecified whether this constructor can result in a null string view (
str.data()
would have to return
nullptr
for this).
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 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. The compatible character types are:
QChar
,
ushort
,
char16_t
and (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
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
() 代替。
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. The compatible character types are:
QChar
,
ushort
,
char16_t
and (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
另请参阅 fromArray .
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. The compatible character types are:
QChar
,
ushort
,
char16_t
and (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
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. The compatible character types are:
QChar
,
ushort
,
char16_t
and (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
Constructs a null string view.
另请参阅 isNull ().
Constructs a null string view.
另请参阅 isNull ().
返回字符位于位置 n in this string view.
The behavior is undefined if n is negative or not less than size ().
另请参阅 operator[] (), front ()，和 back ().
Returns the last character in the string. Same as last ().
This function is provided for STL compatibility.
警告： Calling this function on an empty string view constitutes undefined behavior.
另请参阅 front (), first ()，和 last ().
返回常量 STL 样式迭代器 pointing to the first character in the string.
This function is provided for STL compatibility.
另请参阅 end (), constBegin (), cbegin (), rbegin ()，和 data ().
如同 begin ().
This function is provided for STL compatibility.
另请参阅 cend (), begin (), constBegin (), crbegin ()，和 data ().
如同 end ().
This function is provided for STL compatibility.
另请参阅 cbegin (), end (), constEnd ()，和 crend ().
Truncates this string view by length 字符。
如同
*this = left(size() - length)
.
注意： The behavior is undefined when length < 0 or length > size ().
另请参阅 mid (), left (), right (), chopped ()，和 truncate ().
返回子字符串长度 size () - length starting at the beginning of this object.
如同
left(size() - length)
.
注意： The behavior is undefined when length < 0 or length > size ().
另请参阅 mid (), left (), right (), chop ()，和 truncate ().
[since 5.12]
int
QStringView::
compare
(
QStringView
str
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
Returns an integer that compares to zero as this string-view compares to the string-view str .
若 cs is Qt::CaseSensitive (the default), the comparison is case sensitive; otherwise the comparison is case-insensitive.
该函数在 Qt 5.12 引入。
另请参阅 operator== (), operator< ()，和 operator> ().
[since 6.1]
QStringView::const_iterator
QStringView::
constBegin
() const
如同 begin ().
该函数在 Qt 6.1 引入。
另请参阅 constEnd (), begin (), cbegin (), crbegin ()，和 data ().
[since 6.0]
QStringView::const_pointer
QStringView::
constData
() const
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.
该函数在 Qt 6.0 引入。
另请参阅 data (), begin (), end ()，和 utf16 ().
[since 6.1]
QStringView::const_iterator
QStringView::
constEnd
() const
如同 end ().
该函数在 Qt 6.1 引入。
另请参阅 constBegin (), end (), cend ()，和 crend ().
[since 6.1]
bool
QStringView::
contains
(const
QRegularExpression
&
re
,
QRegularExpressionMatch
*
rmatch
= nullptr) const
返回
true
if the regular expression
re
matches somewhere in this string view; otherwise returns
false
.
If the match is successful and
rmatch
不是
nullptr
, it also writes the results of the match into the
QRegularExpressionMatch
object pointed to by
rmatch
.
该函数在 Qt 6.1 引入。
另请参阅 QRegularExpression::match ().
[since 6.1]
qsizetype
QStringView::
count
(const
QRegularExpression
&
re
) const
Returns the number of times the regular expression re matches in the string view.
For historical reasons, this function counts overlapping matches. This behavior is different from simply iterating over the matches in the string using QRegularExpressionMatchIterator .
该函数在 Qt 6.1 引入。
另请参阅 QRegularExpression::globalMatch ().
[since 6.0]
qsizetype
QStringView::
count
(
QChar
ch
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
This function overloads count().
Returns the number of occurrences of the character ch in the string reference.
若 cs is Qt::CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 6.0 引入。
另请参阅 QString::count (), contains ()，和 indexOf ().
[since 6.0]
qsizetype
QStringView::
count
(
QStringView
str
,
Qt::CaseSensitivity
cs
= Qt::CaseSensitive) const
This function overloads count().
Returns the number of (potentially overlapping) occurrences of the string reference str in this string reference.
若 cs is Qt::CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 6.0 引入。
另请参阅 QString::count (), contains ()，和 indexOf ().
如同 rbegin ().
This function is provided for STL compatibility.
另请参阅 crend (), rbegin ()，和 cbegin ().
如同 rend ().
This function is provided for STL compatibility.
另请参阅 crbegin (), rend ()，和 cend ().
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 begin (), end ()，和 utf16 ().
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 (), size ()，和 length ().
返回常量 STL 样式迭代器 pointing to the imaginary character after the last character in the list.
This function is provided for STL compatibility.
另请参阅 begin (), constEnd (), cend ()，和 rend ().
[since 6.0]
QStringView
QStringView::
first
(
qsizetype
n
) const
Returns a string view that points to the first n characters of this string.
注意： The behavior is undefined when n < 0 or n > size ().
该函数在 Qt 6.0 引入。
另请参阅 last (), sliced (), startsWith (), chopped (), chop ()，和 truncate ().
Returns the first character in the string. Same as front ().
This function is provided for compatibility with other Qt containers.
警告： Calling this function on an empty string view constitutes undefined behavior.
另请参阅 front (), back ()，和 last ().
[static]
template <typename Char, size_t Size, if_compatible_char<Char>>
QStringView
QStringView::
fromArray
(const
Char
(&)[
Size
]
string
= Size)
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:
QChar
,
ushort
,
char16_t
and (on platforms, such as Windows, where it is a 16-bit type)
wchar_t
.
Returns the first character in the string. Same as first ().
This function is provided for STL compatibility.
警告： Calling this function on an empty string view constitutes undefined behavior.
另请参阅 back (), first ()，和 last ().
[since 6.1]
qsizetype
QStringView::
indexOf
(const
QRegularExpression
&
re
,
qsizetype
from
= 0,
QRegularExpressionMatch
*
rmatch
= nullptr) const
Returns the index position of the first match of the regular expression re in the string view, searching forward from index position from . Returns -1 if re didn't match anywhere.
If the match is successful and
rmatch
不是
nullptr
, it also writes the results of the match into the
QRegularExpressionMatch
object pointed to by
rmatch
.
注意： Due to how the regular expression matching algorithm works, this function will actually match repeatedly from the beginning of the string view until the position from is reached.
该函数在 Qt 6.1 引入。
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 (), size ()，和 length ().
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 (), size ()，和 length ().
[since 5.11]
bool
QStringView::
isRightToLeft
() const
返回
true
if the string is read right to left.
该函数在 Qt 5.11 引入。
另请参阅 QString::isRightToLeft ().
[since 5.15]
bool
QStringView::
isValidUtf16
() const
返回
true
if the string contains valid UTF-16 encoded data, or
false
否则。
Note that this function does not perform any special validation of the data; it merely checks if it can be successfully decoded from UTF-16. The data is assumed to be in host byte order; the presence of a BOM is meaningless.
该函数在 Qt 5.15 引入。
另请参阅 QString::isValidUtf16 ().
[since 6.0]
QStringView
QStringView::
last
(
qsizetype
n
) const
Returns a string view that points to the last n characters of this string.
注意： The behavior is undefined when n < 0 or n > size ().
该函数在 Qt 6.0 引入。
另请参阅 first (), sliced (), endsWith (), chopped (), chop ()，和 truncate ().
Returns the last character in the string. Same as back ().
This function is provided for compatibility with other Qt containers.
警告： Calling this function on an empty string view constitutes undefined behavior.
另请参阅 back (), front ()，和 first ().
[since 6.2]
qsizetype
QStringView::
lastIndexOf
(const
QRegularExpression
&
re
,
QRegularExpressionMatch
*
rmatch
= nullptr) const
Returns the index position of the last match of the regular expression re in the string view. Returns -1 if re didn't match anywhere.
If the match is successful and
rmatch
不是
nullptr
, it also writes the results of the match into the
QRegularExpressionMatch
object pointed to by
rmatch
.
注意： Due to how the regular expression matching algorithm works, this function will actually match repeatedly from the beginning of the string view until the end of the string view is reached.
该函数在 Qt 6.2 引入。
[since 6.1]
qsizetype
QStringView::
lastIndexOf
(const
QRegularExpression
&
re
,
qsizetype
from
,
QRegularExpressionMatch
*
rmatch
= nullptr) const
Returns the index position of the last match of the regular expression re in the string view, which starts before the index position from 。若 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 re didn't match anywhere.
If the match is successful and
rmatch
不是
nullptr
, it also writes the results of the match into the
QRegularExpressionMatch
object pointed to by
rmatch
.
注意： Due to how the regular expression matching algorithm works, this function will actually match repeatedly from the beginning of the string view until the position from is reached.
注意：
When searching for a regular expression
re
that may match 0 characters, 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 string 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.
该函数在 Qt 6.1 引入。
如同 size ().
This function is provided for compatibility with other Qt containers.
另请参阅 empty (), isEmpty (), isNull ()，和 size ().
返回常量 STL-style reverse iterator pointing to the first character in the string, in reverse order.
This function is provided for STL compatibility.
另请参阅 rend (), crbegin ()，和 begin ().
返回 STL-style reverse iterator pointing to one past the last character in the string, in reverse order.
This function is provided for STL compatibility.
另请参阅 rbegin (), crend ()，和 end ().
Returns the size of this string view, in UTF-16 code points (that is, surrogate pairs count as two for the purposes of this function, the same as in QString ).
另请参阅 empty (), isEmpty (), isNull ()，和 length ().
[since 6.0]
QStringView
QStringView::
sliced
(
qsizetype
pos
,
qsizetype
n
) const
Returns a string view that points to n characters of this string, starting at position pos .
注意： The behavior is undefined when pos < 0, n < 0, or pos + n > size ().
该函数在 Qt 6.0 引入。
另请参阅 first (), last (), chopped (), chop ()，和 truncate ().
[since 6.0]
QStringView
QStringView::
sliced
(
qsizetype
pos
) const
这是重载函数。
Returns a string view starting at position pos in this object, and extending to its end.
注意： The behavior is undefined when pos < 0 or pos > size ().
该函数在 Qt 6.0 引入。
另请参阅 first (), last (), chopped (), chop ()，和 truncate ().
[since 6.0]
QList
<
QStringView
> QStringView::
split
(const
QRegularExpression
&
re
,
Qt::SplitBehavior
behavior
= Qt::KeepEmptyParts) const
Splits the string into substring views wherever the regular expression re matches, and returns the list of those strings. If re does not match anywhere in the string, split() returns a single-element list containing this string as view.
注意： The views in the returned list are sub-views of this view; as such, they reference the same data as it and only remain valid for as long as that data remains live.
该函数在 Qt 6.0 引入。
[since 6.0]
CFStringRef
QStringView::
toCFString
() const
Creates a CFString from this QStringView .
The caller owns the CFString and is responsible for releasing it.
注意： this function is only available on macOS and iOS.
该函数在 Qt 6.0 引入。
[since 6.0]
double
QStringView::
toDouble
(
bool
*
ok
= nullptr) const
Returns the string converted to a
double
值。
Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toDouble ()
For historic reasons, this function does not handle thousands group separators. If you need to convert such numbers, use QLocale::toDouble ().
该函数在 Qt 6.0 引入。
另请参阅 QString::toDouble ().
[since 6.0]
float
QStringView::
toFloat
(
bool
*
ok
= nullptr) const
Returns the string converted to a
float
值。
Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toFloat ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toFloat ().
[since 6.0]
int
QStringView::
toInt
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to an
int
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toInt ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toInt ().
Returns a Latin-1 representation of the string as a QByteArray .
The behavior is undefined if the string contains non-Latin1 characters.
另请参阅 toUtf8 (), toLocal8Bit ()，和 QStringEncoder .
Returns a local 8-bit representation of the string as a QByteArray .
On Unix systems this is equivalen to toUtf8 (), on Windows the systems current code page is being used.
The behavior is undefined if the string contains characters not supported by the locale's 8-bit encoding.
另请参阅 toLatin1 (), toUtf8 ()，和 QStringEncoder .
[since 6.0]
long
QStringView::
toLong
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to a
long
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toLong ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toLong ().
[since 6.0]
qlonglong
QStringView::
toLongLong
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to a
long long
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toLongLong ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toLongLong ().
[since 6.0]
NSString
*QStringView::
toNSString
() const
Creates an NSString from this QStringView .
The NSString is autoreleased.
注意： this function is only available on macOS and iOS.
该函数在 Qt 6.0 引入。
[since 6.0]
short
QStringView::
toShort
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to a
short
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toShort ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toShort ().
Returns a deep copy of this string view's data as a QString .
The return value will be the null QString if and only if this string view is null.
警告：
QStringView
can store strings with more than 2
30
characters while
QString
cannot. Calling this function on a string view for which
size
() returns a value greater than
INT_MAX / 2
constitutes undefined behavior.
[since 6.0]
uint
QStringView::
toUInt
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to an
无符号 int
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toUInt ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toUInt ().
[since 6.0]
ulong
QStringView::
toULong
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to an
unsigned long
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toULongLong ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toULong ().
[since 6.0]
qulonglong
QStringView::
toULongLong
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to an
unsigned long long
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toULongLong ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toULongLong ().
[since 6.0]
ushort
QStringView::
toUShort
(
bool
*
ok
= nullptr,
int
base
= 10) const
Returns the string converted to an
unsigned short
using base
base
, which is 10 by default and must be between 2 and 36, or 0. Returns 0 if the conversion fails.
若
ok
不是
nullptr
, failure is reported by setting *
ok
to
false
, and success by setting *
ok
to
true
.
若 base is 0, the C language convention is used: If the string begins with "0x", base 16 is used; if the string begins with "0", base 8 is used; otherwise, base 10 is used.
The string conversion will always happen in the 'C' locale. For locale dependent conversion use QLocale::toUShort ()
该函数在 Qt 6.0 引入。
另请参阅 QString::toUShort ().
Returns a UCS-4/UTF-32 representation of the string as a QList <uint>.
UCS-4 is a Unicode codec and therefore it is lossless. All characters from this string will be encoded in UCS-4. Any invalid sequence of code units in this string is replaced by the Unicode replacement character (
QChar::ReplacementCharacter
, which corresponds to
U+FFFD
).
The returned list is not 0-terminated.
另请参阅 toUtf8 (), toLatin1 (), toLocal8Bit ()，和 QStringEncoder .
Returns a UTF-8 representation of the string as a QByteArray .
UTF-8 is a Unicode codec and can represent all characters in a Unicode string like QString .
另请参阅 toLatin1 (), toLocal8Bit ()，和 QStringEncoder .
[since 5.14]
qsizetype
QStringView::
toWCharArray
(
wchar_t
*
array
) const
Transcribes this string into the given array .
The caller is responsible for ensuring
array
is large enough to hold the
wchar_t
encoding of this string (allocating the array with the same length as the string is always sufficient). The array is encoded in UTF-16 on platforms where
wchar_t
is 2 bytes wide (e.g. Windows); otherwise (Unix systems),
wchar_t
is assumed to be 4 bytes wide and the data is written in UCS-4.
注意： This function writes no null terminator to the end of array .
Returns the number of
wchar_t
entries written to
array
.
该函数在 Qt 5.14 引入。
另请参阅 QString::toWCharArray ().
Strips leading and trailing whitespace and returns the result.
Whitespace means any character for which
QChar::isSpace
() 返回
true
. This includes the ASCII characters '\t', '\n', '\v', '\f', '\r', and ' '.
Truncates this string view to length length .
如同
*this = left(length)
.
注意： The behavior is undefined when length < 0 or length > size ().
另请参阅 mid (), left (), right (), chopped ()，和 chop ().
Returns a const pointer to the first character in the string.
storage_type
is
char16_t
.
注意： The character array represented by the return value is not null-terminated.
另请参阅 begin (), end ()，和 data ().
返回字符位于位置 n in this string view.
The behavior is undefined if n is negative or not less than size ().
另请参阅 at (), front ()，和 back ().
Operators for comparing lhs to rhs .
另请参阅 compare ().
[since 5.10]
size_t
qHash
(
QStringView
key
,
size_t
seed
= 0)
返回哈希值为 key ，使用 seed 做计算种子。
该函数在 Qt 5.10 引入。