Debugging Qt applications

To debug any Qt application, you need to ensure that you have installed the debug symbols of the Qt libraries. On Windows, they are installed together with release version DLLs. Meanwhile, on Linux, you may need to install debug symbols by the distribution's package manager.

Some developers tend to use a function similar to printf to debug the application. Qt provides four global functions, which are shown in the following table, to print out debug, warnings, and error text:

Function	Usage
qDebug()	This function is used for writing custom debug output.
qWarning()	This function is used for reporting warnings and recoverable errors.
qCritical()	This function is used for writing critical error messages and reporting system errors.
qFatal()	This function is used for printing fatal error messages shortly before exiting.

Normally, you can just use a C-style method similar to printf.

qDebug("Hello %s", "World!");

However, in most cases, we'll include the...