QDebug 类

QDebug 类为调试信息提供输出流。更多...

头：	#include <QDebug>
qmake:	QT += core

所有成员列表，包括继承成员

公共类型

enum	VerbosityLevel { MinimumVerbosity, DefaultVerbosity, MaximumVerbosity }

公共函数

	QDebug (const QDebug & o )
	QDebug (QtMsgType t )
	QDebug (QString * string )
	QDebug (QIODevice * device )
QDebug &	operator= (const QDebug & other )
	~QDebug ()
bool	autoInsertSpaces () const
QDebug &	maybeQuote (char c = '"')
QDebug &	maybeSpace ()
QDebug &	noquote ()
QDebug &	nospace ()
QDebug &	quote ()
QDebug &	resetFormat ()
void	setAutoInsertSpaces (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 )
QDebug &	operator<< (const QString & t )
QDebug &	operator<< (const QStringRef & t )
QDebug &	operator<< (QStringView s )
QDebug &	operator<< (QLatin1String t )
QDebug &	operator<< (const QByteArray & t )
QDebug &	operator<< (const void * t )

QDebug	operator<< (QDebug debug , const QFlags<T> & flags )
QDebug	operator<< (QDebug debug , const QList<T> & list )
QDebug	operator<< (QDebug debug , const QVector<T> & vec )
QDebug	operator<< (QDebug debug , const std::vector<T, Alloc> & vec )
QDebug	operator<< (QDebug debug , const std::list<T, Alloc> & vec )
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 QMap<Key, T> & map )
QDebug	operator<< (QDebug debug , const QHash<Key, T> & hash )
QDebug	operator<< (QDebug debug , const QPair<T1, T2> & pair )
QDebug	operator<< (QDebug debug , const QSet<T> & set )

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`

该枚举在 Qt 5.13 引入或被修改。

另请参阅 verbosity () 和 setVerbosity ().

成员函数文档编制

QDebug:: QDebug (const QDebug & o )

Constructs a copy of the other debug stream o .

QDebug:: QDebug ( QtMsgType t )

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

QDebug:: QDebug ( QString * string )

Constructs a debug stream that writes to the given string .

QDebug:: QDebug ( QIODevice * device )

Constructs a debug stream that writes to the given device .

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

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

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.

该函数在 Qt 5.0 引入。

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 " .

该函数在 Qt 5.4 引入。

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.

该函数在 Qt 5.4 引入。

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.

该函数在 Qt 5.4 引入。

另请参阅 noquote () 和 maybeQuote ().

QDebug &QDebug:: resetFormat ()

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

该函数在 Qt 5.4 引入。

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.

该函数在 Qt 5.0 引入。

另请参阅 autoInsertSpaces () 和 QDebugStateSaver .

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。

该函数在 Qt 5.6 引入。

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 ().

void QDebug:: swap ( QDebug & other )

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

该函数在 Qt 5.0 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。

该函数在 Qt 5.13 引入。

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。

该函数在 Qt 5.6 引入。

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.

该函数在 Qt 5.5 引入。

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

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

该函数在 Qt 5.5 引入。

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 string, t , to the stream and returns a reference to the stream. The string is never quoted nor transformed to the output, but note that some QDebug backends might not be 8-bit clean.

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).