QByteArrayView 类提供字节数组视图，带有只读子集的 QByteArray API. 更多...
| 头： | #include <QByteArrayView> |
| 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 .
| const_iterator | |
| const_pointer | |
| const_reference | |
| const_reverse_iterator | |
| difference_type | |
| iterator | |
| pointer | |
| reference | |
| reverse_iterator | |
| size_type | |
| storage_type | |
| value_type |
| QByteArrayView (const char (&)[Size] data = Size) | |
| QByteArrayView (const Container & c ) | |
| QByteArrayView (const QByteArray & byteArray ) | |
| QByteArrayView (const Byte * data ) | |
| QByteArrayView (const Byte * first , const Byte * last ) | |
| QByteArrayView (const Byte * data , qsizetype len ) | |
| QByteArrayView (std::nullptr_t) | |
| QByteArrayView () | |
| char | at (qsizetype n ) const |
| char | back () const |
| QByteArrayView::const_iterator | begin () const |
| QByteArrayView::const_iterator | cbegin () const |
| QByteArrayView::const_iterator | cend () const |
| void | chop (qsizetype length ) |
| QByteArrayView | chopped (qsizetype length ) const |
| int | compare (QByteArrayView bv , Qt::CaseSensitivity cs = Qt::CaseSensitive) const |
| QByteArrayView::const_pointer | constData () const |
| bool | contains (QByteArrayView bv ) const |
| bool | contains (char ch ) const |
| qsizetype | count (QByteArrayView bv ) const |
| qsizetype | count (char ch ) const |
| QByteArrayView::const_reverse_iterator | crbegin () const |
| QByteArrayView::const_reverse_iterator | crend () const |
| QByteArrayView::const_pointer | data () const |
| bool | empty () const |
| QByteArrayView::const_iterator | end () const |
| bool | endsWith (QByteArrayView bv ) const |
| bool | endsWith (char ch ) const |
| QByteArrayView | first (qsizetype n ) const |
| char | front () const |
| qsizetype | indexOf (QByteArrayView bv , qsizetype from = 0) const |
| qsizetype | indexOf (char ch , qsizetype from = 0) const |
| bool | isEmpty () const |
| bool | isNull () const |
| QByteArrayView | last (qsizetype n ) const |
| qsizetype | lastIndexOf (QByteArrayView bv , qsizetype from ) const |
| qsizetype | lastIndexOf (QByteArrayView bv ) const |
| qsizetype | lastIndexOf (char ch , qsizetype from = -1) const |
| qsizetype | length () const |
| QByteArrayView::const_reverse_iterator | rbegin () const |
| QByteArrayView::const_reverse_iterator | rend () const |
| qsizetype | size () const |
| QByteArrayView | sliced (qsizetype pos ) const |
| QByteArrayView | sliced (qsizetype pos , qsizetype n ) const |
| bool | startsWith (QByteArrayView bv ) const |
| bool | startsWith (char ch ) const |
| QByteArray | toByteArray () const |
| void | truncate (qsizetype length ) |
| char | operator[] (qsizetype n ) const |
| QByteArrayView | fromArray (const Byte (&)[Size] data = Size) |
| bool | operator!= (QByteArrayView lhs , QByteArrayView rhs ) |
| bool | operator< (QByteArrayView lhs , QByteArrayView rhs ) |
| bool | operator<= (QByteArrayView lhs , QByteArrayView rhs ) |
| bool | operator== (QByteArrayView lhs , QByteArrayView rhs ) |
| bool | operator> (QByteArrayView lhs , QByteArrayView rhs ) |
| bool | operator>= (QByteArrayView lhs , QByteArrayView rhs ) |
A QByteArrayView references a contiguous portion of raw bytes it does not own. It acts as an interface type to all kinds of byte-array-like data, without the need to construct a QByteArray 首先。
The byte array data may be represented as an array (or an array-compatible data-structure such as
QByteArray
, std::basic_string, etc.) of
char
,
signed char
,
unsigned char
or
std::byte
.
QByteArrayView is designed as an interface type; its main use-case is as a function parameter type. When QByteArrayViews are used as automatic variables or data members, care must be taken to ensure that the referenced data (for example, owned by a QByteArray ) outlives the QByteArrayView on all code paths, lest the byte array view ends up referencing deleted data.
When used as an interface type, QByteArrayView allows a single function to accept a wide variety of byte-array-like data sources. One function accepting QByteArrayView thus replaces several function overloads (taking, for example, QByteArray , const char *, etc.) while at the same time enabling even more byte array data sources to be passed to the function.
QByteArrayView should be passed by value, not by reference-to-const:
void myfun1(QByteArrayView bv); // preferred
void myfun2(const QByteArrayView &bv); // compiles and works, but slower
If you want to give your users maximum freedom in what type of data they can pass to your function, accompany the QByteArrayView overload with overloads for
void fun(QByteArrayView bv);
void fun(char ch) { fun(QByteArrayView(&ch, 1)); }
even though, for technical reasons, QByteArrayView cannot provide a char constructor by itself.
QByteArrayView can also be used as the return value of a function. If you call a function returning QByteArrayView, take extra care to not keep the QByteArrayView around longer than the function promises to keep the referenced data alive. If in doubt, obtain a strong reference to the data by calling toByteArray () to convert the QByteArrayView into a QByteArray .
QByteArrayView can be constructed on any container of bytes, where the byte type is one of:
char
(有符号和无符号两者)
std::byte
另请参阅 QByteArray and QStringView .
此 typedef 提供 STL 样式 const 迭代器为 QByteArrayView .
另请参阅 iterator and const_reverse_iterator .
别名化的
value_type *
。为兼容 STL (标准模板库) 提供。
别名化的
value_type &
。为兼容 STL (标准模板库) 提供。
This typedef provides an STL-style const reverse iterator for QByteArrayView .
另请参阅 reverse_iterator and const_iterator .
别名化的
std::ptrdiff_t
。为兼容 STL (标准模板库) 提供。
此 typedef 提供 STL 样式 const 迭代器为 QByteArrayView .
QByteArrayView 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 *
。为兼容 STL (标准模板库) 提供。
QByteArrayView does not support mutable pointers, so this is the same as const_pointer .
别名化的
value_type &
。为兼容 STL (标准模板库) 提供。
QByteArrayView does not support mutable references, so this is the same as const_reference .
This typedef provides an STL-style const reverse iterator for QByteArrayView .
QByteArrayView does not support mutable reverse iterators, so this is the same as const_reverse_iterator .
另请参阅 const_reverse_iterator and iterator .
别名化的 qsizetype。为兼容 STL (标准模板库) 提供。
别名化的
char
.
别名化的
const char
。为兼容 STL (标准模板库) 提供。
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 。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 no match is found.
注意：
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.
另请参阅 indexOf () 和 contains ().
返回
true
if this byte array view contains an occurrence of the sequence of bytes viewed by
bv
or character
ch
, respectively; otherwise returns
false
.
另请参阅 indexOf () 和 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.
若 from is -1, the search starts at the last character; if it is -2, at the next to last character and so on.
另请参阅 lastIndexOf () 和 contains ().
返回
true
if this byte array view ends with byte array view
bv
or character
ch
, respectively; otherwise returns
false
.
另请参阅 startsWith ().
返回
true
if this byte array view starts with byte array view
bv
or character
ch
, respectively; otherwise returns
false
.
另请参阅 endsWith ().
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
() 代替。
data must remain valid for the lifetime of this byte array view object.
注意：
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.
另请参阅 fromArray .
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)
分别。
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.
另请参阅 兼容字节类型 .
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()
.
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.
传递
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.
另请参阅 兼容字节类型 .
Constructs a byte array view on first 按长度 ( last - first ).
范围
[first,last)
must remain valid for the lifetime of this QByteArrayView.
传递
\nullptr
as
first
是安全的若
last
is
nullptr
, too, and results in a null byte array view.
行为未定义若
last
precedes
first
，或
first
is
nullptr
and
last
is not.
This constructor only participates in overload resolution if
Byte
is a compatible byte type.
另请参阅 兼容字节类型 .
Constructs a byte array view on data 按长度 len .
范围
[data,len)
must remain valid for the lifetime of this QByteArrayView.
传递
nullptr
as
data
是安全的若
len
is 0, too, and results in a null byte array view.
行为未定义若
len
is negative or, when positive, if
data
is
nullptr
.
This constructor only participates in overload resolution if
Byte
is a compatible byte type.
另请参阅 兼容字节类型 .
Constructs a null byte array view.
另请参阅 isNull ().
Constructs a null byte array view.
另请参阅 isNull ().
返回字符位于位置 n in this byte array view.
行为未定义若 n is negative or not less than size ().
另请参阅 operator[] (), front ()，和 back ().
Returns the last byte in the byte array.
此函数为兼容 STL (标准模板库) 提供。
警告： Calling this function on an empty byte array view constitutes undefined behavior.
另请参阅 front ().
返回常量 STL 样式迭代器 pointing to the first byte in the byte array.
此函数为兼容 STL (标准模板库) 提供。
另请参阅 end (), cbegin (), rbegin ()，和 data ().
如同 begin ().
此函数为兼容 STL (标准模板库) 提供。
另请参阅 cend (), begin (), crbegin ()，和 data ().
如同 end ().
此函数为兼容 STL (标准模板库) 提供。
另请参阅 cbegin (), end ()，和 crend ().
Truncates this byte array view by length 字符。
如同
*this = first(size() - length)
.
注意： 行为未定义当 length < 0 or length > size ().
另请参阅 sliced (), first (), last (), chopped ()，和 truncate ().
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 起始于此对象的开头。
如同
first(size() - length)
.
注意： 行为未定义当 length < 0 or length > size ().
另请参阅 first (), last (), sliced (), chop ()，和 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 .
该函数在 Qt 6.2 引入。
另请参阅 operator== ().
返回常量
char
pointer to the first byte in the byte array.
注意： 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 ().
另请参阅 data (), begin ()，和 end ().
Returns the number of (potentially overlapping) occurrences of the sequence of bytes viewed by bv in this byte array view.
另请参阅 contains () 和 indexOf ().
这是重载函数。
Returns the number of occurrences of byte ch in this byte array view.
另请参阅 contains () 和 indexOf ().
如同 rbegin ().
此函数为兼容 STL (标准模板库) 提供。
另请参阅 crend (), rbegin ()，和 cbegin ().
如同 rend ().
此函数为兼容 STL (标准模板库) 提供。
另请参阅 crbegin (), rend ()，和 cend ().
返回常量
char
pointer to the first byte in the byte array.
注意： 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 ().
返回
true
if this byte array view is empty - that is,
size() == 0
.
此函数为兼容 STL (标准模板库) 提供。
另请参阅 isEmpty (), isNull ()，和 size ().
返回常量 STL 样式迭代器 pointing just after the last byte in the byte array.
此函数为兼容 STL (标准模板库) 提供。
另请参阅 begin (), cend ()，和 rend ().
Returns a byte array view that points to the first
n
bytes of this byte array view. Equivalent to
sliced(0, n)
.
注意： 行为未定义当 n < 0 or n > size ().
另请参阅 last (), startsWith (), chopped (), chop ()，和 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.
另请参阅 兼容字节类型 and QByteArrayView .
Returns the first byte in the byte array.
此函数为兼容 STL (标准模板库) 提供。
警告： Calling this function on an empty byte array view constitutes undefined behavior.
另请参阅 back ().
返回
true
if this byte array view is empty - that is,
size() == 0
.
另请参阅 empty (), isNull ()，和 size ().
返回
true
if this byte array view is null - that is,
data() == nullptr
.
另请参阅 empty (), isEmpty ()，和 size ().
Returns a byte array view that points to the last n bytes of this byte array view.
注意： 行为未定义当 n < 0 or n > size ().
另请参阅 first (), endsWith (), chopped (), chop ()，和 truncate ().
[since 6.2]
qsizetype
QByteArrayView::
lastIndexOf
(
QByteArrayView
bv
) const
这是重载函数。
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.
该函数在 Qt 6.2 引入。
另请参阅 indexOf () 和 contains ().
如同 size ().
另请参阅 empty (), isEmpty (), isNull ()，和 size ().
返回常量 STL-style reverse iterator pointing to the first byte in the byte array, in reverse order.
此函数为兼容 STL (标准模板库) 提供。
另请参阅 rend (), crbegin ()，和 begin ().
返回 STL-style reverse iterator pointing to one past the last byte in the byte array, in reverse order.
此函数为兼容 STL (标准模板库) 提供。
另请参阅 rbegin (), crend ()，和 end ().
Returns the number of bytes in this byte array view.
另请参阅 empty (), isEmpty ()，和 isNull ().
Returns a byte array view starting at position pos in this object, and extending to its end.
注意： 行为未定义当 pos < 0 or pos > size ().
另请参阅 first (), last (), chopped (), chop ()，和 truncate ().
Returns a byte array view that points to n bytes of this byte array view, starting at position pos .
注意： 行为未定义当 pos < 0, n < 0, or pos + n > size ().
另请参阅 first (), last (), chopped (), chop ()，和 truncate ().
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.
警告：
QByteArrayView
can store data with more than 2
31
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.
Truncates this byte array view to length length .
如同
*this = first(length)
.
注意： 行为未定义当 length < 0 or length > size ().
另请参阅 first (), last (), sliced (), chopped ()，和 chop ().
返回字符位于位置 n in this byte array view.
行为未定义若 n is negative or not less than size ().
另请参阅 at (), front ()，和 back ().
Comparison operators for QByteArrayView .