QDebug lines

gRicky

Hi ALL,

I'm wondering what happen to the qDebug() lines I've written on my code when I build the app for release. Does this code make the app more heavy and slow?

tilsitt

Hi,

Your qDebug() lines will be ouputed unless you define QT_NO_DEBUG_OUTPUT during compilation (even if you are in release mode). If you didn't specify a message handler, stderr will be used, and yes it will make the app slower if you're writing too much. So, just define QT_NO_DEBUG_OUTPUT where you are in release mode.

gRicky

I have added what you have suggested to add to my project file but it seems it doesn't work. I launched the app on Qt using the run button and I have looked at the output window on Qt and the qDebug() lines still apear so, how can I check if the added line stops the qDebug() lines, properly?

Here the code I have added to the project file:
@
CONFIG -= debug
CONFIG += release

release {
message(Release build!)
DEFINES += QT_NO_DEBUG_OUTPUT
}

debug {
message(Debug build!)
DEFINES += DEBUG
}
@

tilsitt

I tried the following to detect debug and release config:

@
CONFIG(debug, debug|release) {
DEFINES += DEBUG
}
else {
DEFINES += QT_NO_DEBUG_OUTPUT
}
@

It works for me to disable qDebug() output.

gRicky

I did it. As before, looking at the output window on qt, after I had launched the executable using the run button, I still can see the qDebug lines are working....

gRicky

[quote author="tilsitt" date="1355915223"]I tried the following to detect debug and release config:

@
CONFIG(debug, debug|release) {
DEFINES += DEBUG
}
else {
DEFINES += QT_NO_DEBUG_OUTPUT
}
@

It works for me to disable qDebug() output.[/quote]

I'm sorry but I'd like to know: where did you add the above lines?
I added my lines on my qt .pro file and it seems they don't work!