Android and fprint(stderr,"%s",message). How?

bogong

Hello all!
I've got issue with custom function for logger that is exchanging standard Qt QDebug(). This function using fprint, something like this:

static void __attribute__((unused)) fLoggerMessageHandler(
	QtMsgType inType, const QMessageLogContext& inContext, const QString& inMessage
) {
...
	fprintf(stderr,"[INF] %s \n",inMessage.toStdString().c_str());
...
}

and registering it in main.cpp:

qInstallMessageHandler(fLoggerMessageHandler);

It's working everywhere but not on Android. Why? What am I missing?

bogong

Finally found solution :-)))) Just been reading carefully manuals :-))))
Here published example for this issue

JonB

@bogong
Please excuse if I am quite wrong, because I don't use Android, but where are you expecting stderr to go to under Android? My briefest search giave me:

By default, the Android system sends stdout and stderr (System.out and System.err) output to /dev/null.

bogong

@JonB I know it. I am trying to make it works. I need to print logs like qDebug.

bogong

All that I found for now this:

But I don't know where to find this header

#include <android/log.h>

jsulm

@bogong You could forward the output to a logfile. See https://stackoverflow.com/questions/14543443/in-c-how-do-you-redirect-stdin-stdout-stderr-to-files-when-making-an-execvp-or

bogong

@jsulm Thx I am already writing it into db. I need exactly to write it in console. For now I've found two ways:

to use <android/log.h>, but I don't know where to find library itself (header file located in $ANDROID_SDK_ROOT/sysroot/usr/include)
to use Log Cat, but it will require me to write Java native component

When I get free time, will look on how it developed in QT Sources.
If anyone knows the solution - write it here please.

bogong

Finally found solution :-)))) Just been reading carefully manuals :-))))
Here published example for this issue