Debugging

[Voldemort]

Hello,

I don't understand the debugging in Qt. I wrote my own little debugging tool which writes my debug texts in a file in the homedir. But I saw there are also Qt debug tools. But where can I see the texts? In a file? Where is that file?

[marcel]

But I saw there are also Qt debug tools.

What tools are you referring to?

You can use qDebug to print messages on the debugger console.

Regards

[jacek]

I saw there are also Qt debug tools. But where can I see the texts? In a file? Where is that file?

By default qDebug() & friends output messages to "stderr", so all you have to do is to run your application from the console.

[Voldemort]

I mean qDebug:
http://doc.trolltech.com/snapshot/debug.html

Where do I find "stderr" or what is it?

[wysota]

stderr is the standard error file handler in C.

http://en.wikipedia.org/wiki/Standard_streams

[Voldemort]

1) I think they will be showed in the konsole window, is that correct?

2) Can I see it also in a file?

3) I guess you can put debug on/off, how do you do that?

[wysota]

1) I think they will be showed in the konsole window, is that correct?

Yes.

2) Can I see it also in a file?

Yes, if you redirect stderr (descriptor no "2") to some file:

./myapp 2> errors.log

3) I guess you can put debug on/off, how do you do that?

http://www.qtcentre.org/forum/f-qt-p...tput-3992.html

Please search the forum before asking such questions next time.

[Voldemort]

I've tested and I have 2 problems:

1) How do you put on/off the debugging in CMake?
2) When I restart my program, the file is emptied and the new text is written in the file. But I want to add the new text at the end of the file. How can I do this?

[marcel]

1. I think the answer is in your other post.
2. Use >> (append ) instead of > when you redirect the app outpout.

Regards

[wysota]

1) How do you put on/off the debugging in CMake?

The same way as everywhere - by defining a proper macro.

[Voldemort]

1. I think the answer is in your other post.

Which post?

2. Use >> (append ) instead of > when you redirect the app outpout.

Works fine.

The same way as everywhere - by defining a proper macro.

And what command has the macro to execute? Which arguments does it need?

[wysota]

And what command has the macro to execute? Which arguments does it need?

Did you read the thread I linked to where it's discussed how to turn off debugging output? You have to define a QT_NO_DEBUG_OUTPUT macro for your application! And please don't ask me how to define macros... (hint: "#define" or "-D" compiler option)

[Voldemort]

I try to compile it:

cmake ../QQMsn -DQT_NO_DEBUG_OUTPUT

cmake ../QQMsn -DQT_NO_DEBUG_OUTPUT

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Output:

Parse error in command line argument: -DQT_NO_DEBUG_OUTPUT
Should be: VAR:type=value
CMake Error: No cmake scrpt provided.
CMake Error: Problem processing arguments. Aborting.

But what is VAR, type and value? I only has a value (QT_NO_DEBUG_OUTPUT), what are the others?

[jacek]

But what is VAR, type and value? I only has a value (QT_NO_DEBUG_OUTPUT), what are the others?

Take a look at CMakeCache.txt file.

If you want to pass something to the compiler use ADD_DEFINITIONS() command in CMakeList.txt:

ADD_DEFINITIONS( -DQT_NO_DEBUG_OUTPUT )