QDebug Class

The QDebug class provides an output stream for debugging information.

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Publié le 27 décembre 2024 - Mis à jour le 27 décembre 2024

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QDebug Class▲

Header: QDebug
CMake:

find_package(Qt6 REQUIRED COMPONENTS Core)

target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake: QT += core
Inherits: QIODeviceBase
Group: QDebug is part of Implicitly Shared Classes

Detailed Description▲

QDebug is used whenever the developer needs to write out debugging or tracing information to a device, file, string or console.

Basic Use▲

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

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

This constructs a QDebug object using the constructor that accepts a QtMsgType value of QtDebugMsg. Similarly, the qWarning(), qCritical() and 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 or any other 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.

Formatting Options▲

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