QDebug 类

QDebug 类为调试信息提供输出流。 更多...

头：	#include <QDebug>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Core) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core
继承：	QIODeviceBase
继承者：	QQmlInfo

• 所有成员列表，包括继承成员
• QDebug 属于 隐式共享类 .

公共类型

enum	VerbosityLevel { MinimumVerbosity, DefaultVerbosity, MaximumVerbosity }

公共函数

	QDebug (QIODevice * device )
	QDebug (QString * string )
	QDebug (QtMsgType t )
	QDebug (const QDebug & o )
	~QDebug ()
bool	autoInsertSpaces () const
QDebug &	maybeQuote (char c = '"')
QDebug &	maybeSpace ()
QDebug &	noquote ()
QDebug &	nospace ()
QDebug &	quote ()
(从 6.7 起) bool	quoteStrings () const
QDebug &	resetFormat ()
void	setAutoInsertSpaces (bool b )
(从 6.7 起) void	setQuoteStrings (bool b )
void	setVerbosity (int verbosityLevel )
QDebug &	space ()
void	swap (QDebug & other )
QDebug &	verbosity (int verbosityLevel )
int	verbosity () const
QDebug &	operator<< (QChar t )
QDebug &	operator<< (bool t )
QDebug &	operator<< (char t )
QDebug &	operator<< (short t )
QDebug &	operator<< (unsigned short t )
QDebug &	operator<< (char16_t t )
QDebug &	operator<< (char32_t t )
QDebug &	operator<< (int t )
QDebug &	operator<< (unsigned int t )
QDebug &	operator<< (long t )
QDebug &	operator<< (unsigned long t )
QDebug &	operator<< (qint64 t )
QDebug &	operator<< (quint64 t )
QDebug &	operator<< (float t )
QDebug &	operator<< (double t )
QDebug &	operator<< (const char * t )
(从 6.0 起) QDebug &	operator<< (const char16_t * t )
QDebug &	operator<< (const QString & t )
QDebug &	operator<< (QStringView s )
(从 6.0 起) QDebug &	operator<< (QUtf8StringView s )
QDebug &	operator<< (QLatin1StringView t )
QDebug &	operator<< (const QByteArray & t )
(从 6.0 起) QDebug &	operator<< (QByteArrayView t )
QDebug &	operator<< (const void * t )
(从 6.7 起) QDebug &	operator<< (std::nullopt_t)
(从 6.5 起) QDebug &	operator<< (const std::basic_string<Char, Args...> & s )
(从 6.5 起) QDebug &	operator<< (std::basic_string_view<Char, Args...> s )
(从 6.6 起) QDebug &	operator<< (std::chrono::duration<Rep, Period> duration )
(从 6.7 起) QDebug &	operator<< (T i128 )
(从 6.7 起) QDebug &	operator<< (T u128 )
QDebug &	operator= (const QDebug & other )

静态公共成员

(从 6.0 起) QString

toString (T && object )

相关非成员

QDebug	operator<< (QDebug debug , const std::list<T, Alloc> & vec )
QDebug	operator<< (QDebug debug , const std::vector<T, Alloc> & vec )
QDebug	operator<< (QDebug debug , const QSet<T> & set )
QDebug	operator<< (QDebug debug , const QMap<Key, T> & map )
QDebug	operator<< (QDebug debug , const QMultiMap<Key, T> & map )
QDebug	operator<< (QDebug debug , const std::map<Key, T, Compare, Alloc> & map )
QDebug	operator<< (QDebug debug , const std::multimap<Key, T, Compare, Alloc> & map )
QDebug	operator<< (QDebug debug , const QHash<Key, T> & hash )
QDebug	operator<< (QDebug debug , const QMultiHash<Key, T> & hash )
QDebug	operator<< (QDebug debug , const std::pair<T1, T2> & pair )
QDebug	operator<< (QDebug debug , const QContiguousCache<T> & cache )
QDebug	operator<< (QDebug debug , const QFlags<T> & flags )
QDebug	operator<< (QDebug debug , const QList<T> & list )
(since 6.3) QDebug	operator<< (QDebug debug , const QVarLengthArray<T, P> & array )

详细描述

就会使用 QDebug，每当开发者需要把调试 (或跟踪) 信息写入输出到设备、文件、字符串或控制台时。

基本用法

In the common case, it is useful to call the qDebug () function to obtain a default QDebug object to use for writing debugging information.

    qDebug() << "Date:" << QDate::currentDate();
    qDebug() << "Types:" << QString("String") << QChar('x') << QRect(0, 10, 50, 40);
    qDebug() << "Custom coordinate type:" << coordinate;
					

This constructs a QDebug object using the constructor that accepts a QtMsgType value of QtDebugMsg 。同样， qWarning (), qCritical () 和 qFatal () functions also return QDebug objects for the corresponding message types.

The class also provides several constructors for other situations, including a constructor that accepts a QFile 或任何其它 QIODevice subclass that is used to write debugging information to files and other devices. The constructor that accepts a QString is used to write to a string for display or serialization.

格式化选项

QDebug formats output so that it's easily readable. It automatically adds spaces between arguments, and adds quotes around QString , QByteArray , QChar 自变量。

可以微调这些选项透过 space (), nospace () 和 quote (), noquote () 方法。此外， QTextStream 操作符 可以管道到 QDebug 流。

QDebugStateSaver limits changes to the formatting to the current scope. resetFormat () resets the options to the default ones.

把自定义类型写入流

Many standard types can be written to QDebug objects, and Qt provides support for most Qt value types. To add support for custom types, you need to implement a streaming operator, as in the following example:

QDebug operator<<(QDebug debug, const Coordinate &c)
{
    QDebugStateSaver saver(debug);
    debug.nospace() << '(' << c.x() << ", " << c.y() << ')';
    return debug;
}
					

This is described in the 调试技术 and 创建自定义 Qt 类型 documents.

成员类型文档编制

enum QDebug:: VerbosityLevel

此枚举描述冗余级别的范围。

常量	值
QDebug::MinimumVerbosity	0
QDebug::DefaultVerbosity	2
QDebug::MaximumVerbosity	7

另请参阅 verbosity () 和 setVerbosity ().

成员函数文档编制

[since 6.5] template <typename Char, typename... Args> QDebug &QDebug:: operator<< (const std::basic_string < Char , Args ...> & s )

[since 6.5] template <typename Char, typename... Args> QDebug &QDebug:: operator<< ( std::basic_string_view < Char , Args ...> s )

Writes the string or string-view s to the stream and returns a reference to the stream.

These operators only participate in overload resolution if Char 是某一

• char
• char8_t (C++20 only)
• char16_t
• char32_t
• wchar_t

该函数在 Qt 6.5 引入。

[since 6.7] template <typename T, QDebug::if_qint128<T> = true> QDebug &QDebug:: operator<< ( T i128 )

[since 6.7] template <typename T, QDebug::if_quint128<T> = true> QDebug &QDebug:: operator<< ( T u128 )

Prints the textual representation of the 128-bit integer i .

注意： This operator is only available if Qt supports 128-bit integer types. If 128-bit integer types are available in your build, but the Qt libraries were compiled without, the operator will print a warning instead.

注意： Because the operator is a function template, no implicit conversions are performed on its argument. It must be exactly qint128/quint128.

该函数在 Qt 6.7 引入。

另请参阅 QT_SUPPORTS_INT128 .

[explicit] QDebug:: QDebug ( QIODevice * device )

Constructs a debug stream that writes to the given device .

[explicit] QDebug:: QDebug ( QString * string )

Constructs a debug stream that writes to the given string .

[explicit] QDebug:: QDebug ( QtMsgType t )

Constructs a debug stream that writes to the handler for the message type t .

QDebug:: QDebug (const QDebug & o )

Constructs a copy of the other debug stream o .

[noexcept] QDebug:: ~QDebug ()

Flushes any pending data to be written and destroys the debug stream.

bool QDebug:: autoInsertSpaces () const

返回 true 若此 QDebug instance will automatically insert spaces between writes.

另请参阅 setAutoInsertSpaces () 和 QDebugStateSaver .

QDebug &QDebug:: maybeQuote ( char c = '"')

Writes a character c to the debug stream, depending on the current setting for automatic insertion of quotes, and returns a reference to the stream.

默认字符是双引号 " .

另请参阅 quote () 和 noquote ().

QDebug &QDebug:: maybeSpace ()

Writes a space character to the debug stream, depending on the current setting for automatic insertion of spaces, and returns a reference to the stream.

另请参阅 space () 和 nospace ().

QDebug &QDebug:: noquote ()

Disables automatic insertion of quotation characters around QChar , QString and QByteArray contents and returns a reference to the stream.

When quoting is disabled, these types are printed without quotation characters and without escaping of non-printable characters.

另请参阅 quote () 和 maybeQuote ().

QDebug &QDebug:: nospace ()

Disables automatic insertion of spaces and returns a reference to the stream.

另请参阅 space () 和 maybeSpace ().

QDebug &QDebug:: quote ()

Enables automatic insertion of quotation characters around QChar , QString and QByteArray contents and returns a reference to the stream.

Quoting is enabled by default.

另请参阅 noquote () 和 maybeQuote ().

[noexcept, since 6.7] bool QDebug:: quoteStrings () const

返回 true 若此 QDebug instance will quote strings streamed into it (which is the default).

该函数在 Qt 6.7 引入。

另请参阅 QDebugStateSaver , quote (), noquote ()，和 setQuoteStrings ().

QDebug &QDebug:: resetFormat ()

Resets the stream formatting options, bringing it back to its original constructed state.

另请参阅 space () 和 quote ().

void QDebug:: setAutoInsertSpaces ( bool b )

Enables automatic insertion of spaces between writes if b is true; otherwise automatic insertion of spaces is disabled.

另请参阅 autoInsertSpaces () 和 QDebugStateSaver .

[since 6.7] void QDebug:: setQuoteStrings ( bool b )

Enables quoting of strings streamed into this QDebug instance if b is true ; otherwise quoting is disabled.

The default is to quote strings.

该函数在 Qt 6.7 引入。

另请参阅 QDebugStateSaver , quote (), noquote ()，和 quoteStrings ().

void QDebug:: setVerbosity ( int verbosityLevel )

Sets the verbosity of the stream to verbosityLevel .

允许范围是从 0 到 7。默认值为 2。

另请参阅 verbosity () 和 VerbosityLevel .

QDebug &QDebug:: space ()

Writes a space character to the debug stream and returns a reference to the stream.

The stream remembers that automatic insertion of spaces is enabled for future writes.

另请参阅 nospace () 和 maybeSpace ().

[noexcept] void QDebug:: swap ( QDebug & other )

Swaps this debug stream instance with other 。此函数非常快且从不失败。

[static, since 6.0] template <typename T> QString QDebug:: toString ( T && object )

流 object 成 QDebug instance that operates on a string, and then returns that string.

This function is useful for cases where you need the textual representation of an object for debugging, but cannot use operator<< 。例如：

    QTRY_VERIFY2(list.isEmpty(), qPrintable(QString::fromLatin1(
        "Expected list to be empty, but it has the following items: %1")).arg(QDebug::toString(list)));
					

The string is streamed using nospace ().

该函数在 Qt 6.0 引入。

QDebug &QDebug:: verbosity ( int verbosityLevel )

Sets the verbosity of the stream to verbosityLevel 并返回流引用。

允许范围是从 0 到 7。默认值为 2。

另请参阅 verbosity (), setVerbosity ()，和 VerbosityLevel .

int QDebug:: verbosity () const

返回调试流的冗余。

Streaming operators can check the value to decide whether verbose output is desired and print more information depending on the level. Higher values indicate that more information is desired.

允许范围是从 0 到 7。默认值为 2。

另请参阅 setVerbosity () 和 VerbosityLevel .

QDebug &QDebug:: operator<< ( QChar t )

Writes the character, t , to the stream and returns a reference to the stream. Normally, QDebug prints control characters and non-US-ASCII characters as their C escape sequences or their Unicode value (\u1234). To print non-printable characters without transformation, enable the noquote () functionality, but note that some QDebug backends may not be 8-bit clean and may not be able to represent t .

QDebug &QDebug:: operator<< ( bool t )

Writes the boolean value, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( char t )

Writes the character, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( short t )

Writes the signed short integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( unsigned short t )

Writes then unsigned short integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( char16_t t )

Writes the UTF-16 character, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( char32_t t )

Writes the UTF-32 character, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( int t )

Writes the signed integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( unsigned int t )

Writes then unsigned integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( long t )

Writes the signed long integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( unsigned long t )

Writes then unsigned long integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( qint64 t )

Writes the signed 64-bit integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( quint64 t )

Writes then unsigned 64-bit integer, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( float t )

Writes the 32-bit floating point number, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< ( double t )

Writes the 64-bit floating point number, t , to the stream and returns a reference to the stream.

QDebug &QDebug:: operator<< (const char * t )

Writes the '\0'-terminated UTF-8 string, t , to the stream and returns a reference to the stream. The string is never quoted or escaped for the output. Note that QDebug buffers internally as UTF-16 and may need to transform to 8-bit using the locale's codec in order to use some backends, which may cause garbled output (mojibake). Restricting to US-ASCII strings is recommended.

[since 6.0] QDebug &QDebug:: operator<< (const char16_t * t )

Writes the u'\0'-terminated UTF-16 string, t , to the stream and returns a reference to the stream. The string is never quoted or escaped for the output. Note that QDebug buffers internally as UTF-16 and may need to transform to 8-bit using the locale's codec in order to use some backends, which may cause garbled output (mojibake). Restricting to US-ASCII strings is recommended.

该函数在 Qt 6.0 引入。

QDebug &QDebug:: operator<< (const QString & t )

写入字符串 t , to the stream and returns a reference to the stream. Normally, QDebug prints the string inside quotes and transforms non-printable characters to their Unicode values (\u1234).

To print non-printable characters without transformation, enable the noquote () functionality. Note that some QDebug backends might not be 8-bit clean.

输出范例：

    QString s;
    s = "a";
    qDebug().noquote() << s;    // prints: a
    qDebug() << s;              // prints: "a"
    s = "\"a\r\n\"";
    qDebug() << s;              // prints: "\"a\r\n\""
    s = "\033";                 // escape character
    qDebug() << s;              // prints: "\u001B"
    s = "\u00AD";               // SOFT HYPHEN
    qDebug() << s;              // prints: "\u00AD"
    s = "\u00E1";               // LATIN SMALL LETTER A WITH ACUTE
    qDebug() << s;              // prints: "á"
    s = "a\u0301";              // "a" followed by COMBINING ACUTE ACCENT
    qDebug() << s;              // prints: "á";
    s = "\u0430\u0301";         // CYRILLIC SMALL LETTER A followed by COMBINING ACUTE ACCENT
    qDebug() << s;              // prints: "а́"
					

QDebug &QDebug:: operator<< ( QStringView s )

Writes the string view, s , to the stream and returns a reference to the stream. Normally, QDebug prints the string inside quotes and transforms non-printable characters to their Unicode values (\u1234).

To print non-printable characters without transformation, enable the noquote () functionality. Note that some QDebug backends might not be 8-bit clean.

见 QString overload for examples.

[since 6.0] QDebug &QDebug:: operator<< ( QUtf8StringView s )

Writes the string view, s , to the stream and returns a reference to the stream.

Normally, QDebug prints the data inside quotes and transforms control or non-US-ASCII characters to their C escape sequences (\xAB). This way, the output is always 7-bit clean and the string can be copied from the output and pasted back into C++ sources, if necessary.

To print non-printable characters without transformation, enable the noquote () functionality. Note that some QDebug backends might not be 8-bit clean.

该函数在 Qt 6.0 引入。

QDebug &QDebug:: operator<< ( QLatin1StringView t )

写入字符串 t , to the stream and returns a reference to the stream. Normally, QDebug prints the string inside quotes and transforms non-printable characters to their Unicode values (\u1234).

To print non-printable characters without transformation, enable the noquote () functionality. Note that some QDebug backends might not be 8-bit clean.

见 QString overload for examples.

QDebug &QDebug:: operator<< (const QByteArray & t )

Writes the byte array, t , to the stream and returns a reference to the stream. Normally, QDebug prints the array inside quotes and transforms control or non-US-ASCII characters to their C escape sequences (\xAB). This way, the output is always 7-bit clean and the string can be copied from the output and pasted back into C++ sources, if necessary.

To print non-printable characters without transformation, enable the noquote () functionality. Note that some QDebug backends might not be 8-bit clean.

输出范例：

    QByteArray ba;
    ba = "a";
    qDebug().noquote() << ba;    // prints: a
    qDebug() << ba;              // prints: "a"
    ba = "\"a\r\n\"";
    qDebug() << ba;              // prints: "\"a\r\n\""
    ba = "\033";                 // escape character
    qDebug() << ba;              // prints: "\x1B"
    ba = "\xC3\xA1";
    qDebug() << ba;              // prints: "\xC3\xA1"
    ba = QByteArray("a\0b", 3);
    qDebug() << ba               // prints: "\a\x00""b"
					

Note how QDebug needed to close and reopen the string in the way C and C++ languages concatenate string literals so that the letter 'b' is not interpreted as part of the previous hexadecimal escape sequence.

[since 6.0] QDebug &QDebug:: operator<< ( QByteArrayView t )

Writes the data of the observed byte array, t , to the stream and returns a reference to the stream.

Normally, QDebug prints the data inside quotes and transforms control or non-US-ASCII characters to their C escape sequences (\xAB). This way, the output is always 7-bit clean and the string can be copied from the output and pasted back into C++ sources, if necessary.

To print non-printable characters without transformation, enable the noquote () functionality. Note that some QDebug backends might not be 8-bit clean.

见 QByteArray overload for examples.

该函数在 Qt 6.0 引入。

QDebug &QDebug:: operator<< (const void * t )

写入指针 t , to the stream and returns a reference to the stream.

[since 6.7] QDebug &QDebug:: operator<< ( std::nullopt_t )

Writes nullopt to the stream.

该函数在 Qt 6.7 引入。

[since 6.6] template <typename Rep, typename Period> QDebug &QDebug:: operator<< ( std::chrono::duration < Rep , Period > duration )

Prints the time duration duration to the stream and returns a reference to the stream. The printed string is the numeric representation of the period followed by the time unit, similar to what the C++ Standard Library would produce with std::ostream .

The unit is not localized.

该函数在 Qt 6.6 引入。

QDebug &QDebug:: operator= (const QDebug & other )

赋值 other debug stream to this stream and returns a reference to this stream.

相关非成员

template <typename T, typename Alloc> QDebug operator<< ( QDebug debug , const std::list < T , Alloc > & vec )

Writes the contents of list vec to debug . T needs to support streaming into QDebug .

template <typename T, typename Alloc> QDebug operator<< ( QDebug debug , const std::vector < T , Alloc > & vec )

Writes the contents of vector vec to debug . T needs to support streaming into QDebug .

template <typename T> QDebug operator<< ( QDebug debug , const QSet < T > & set )

Writes the contents of set to debug . T needs to support streaming into QDebug .

template <typename Key, typename T> QDebug operator<< ( QDebug debug , const QMap < Key , T > & map )

Writes the contents of map to debug . Both Key and T need to support streaming into QDebug .

template <typename Key, typename T> QDebug operator<< ( QDebug debug , const QMultiMap < Key , T > & map )

Writes the contents of map to debug . Both Key and T need to support streaming into QDebug .

template <typename Key, typename T, typename Compare, typename Alloc> QDebug operator<< ( QDebug debug , const std::map < Key , T , 比较 , Alloc > & map )

Writes the contents of map to debug . Both Key and T need to support streaming into QDebug .

template <typename Key, typename T, typename Compare, typename Alloc> QDebug operator<< ( QDebug debug , const std::multimap < Key , T , 比较 , Alloc > & map )

Writes the contents of map to debug . Both Key and T need to support streaming into QDebug .

template <typename Key, typename T> QDebug operator<< ( QDebug debug , const QHash < Key , T > & hash )

Writes the contents of hash to debug . Both Key and T need to support streaming into QDebug .

template <typename Key, typename T> QDebug operator<< ( QDebug debug , const QMultiHash < Key , T > & hash )

Writes the contents of hash to debug . Both Key and T need to support streaming into QDebug .

template <typename T1, typename T2> QDebug operator<< ( QDebug debug , const std::pair < T1 , T2 > & pair )

Writes the contents of pair to debug . Both T1 and T2 need to support streaming into QDebug .

template <typename T> QDebug operator<< ( QDebug debug , const QContiguousCache < T > & cache )

Writes the contents of cache to debug . T needs to support streaming into QDebug .

template <typename T> QDebug operator<< ( QDebug debug , const QFlags < T > & flags )

写入 flags to debug .

template <typename T> QDebug operator<< ( QDebug debug , const QList < T > & list )

Writes the contents of list to debug . T needs to support streaming into QDebug .

[since 6.3] template <typename T, qsizetype P> QDebug operator<< ( QDebug debug , const QVarLengthArray < T , P > & array )

Writes the contents of array to debug . T needs to support streaming into QDebug .

该函数在 Qt 6.3 引入。

内容

• 公共类型

• 公共函数

• 静态公共成员

• 相关非成员

• 详细描述

• 基本用法

• 格式化选项

• 把自定义类型写入流