How can I see the content of char readline[16] when debugging in QtCreator C++? [SOLVED]

vincegata

Hello,

I am running Qt Creator in Ubuntu, C++ project.

I have a variable char readline [16]. When debugging how can I see the content of this variable? Locals and Expressions window shows the address of the first element, so does the Watch window.

Thanks!

GentooXativa

Try this :P

@
#include <QDebug>
qDebug() << readline[16];
@

vincegata

I can just use cout << readline; instead. I mean, how can I see it in a debugging window without entering any additional code? If I have a dozen of C-style strings I do not want to add some debugging code in every place those strings are used.

Thanatos.jsse

I recommend you read the "documentation.":http://doc.qt.nokia.com/qtcreator-snapshot/creator-debug-mode.html#locals-and-expressions

Qt Creator allow you interact with variables.

BR,

goetz

Just set a breakpoint at the line of interest. The "locals and expressions" tab of the debugger lists all variables in the current method, including the this pointer. Your readline variable should show up there. It also should have a + signe or a triangle the left, you can expand it and it shows you the contents of the array then. If you use a char * instead, it is treated as a string and the string is displayed directly.

Find more infos about the debugger in the "respective section":http://doc.qt.nokia.com/qtcreator-2.4/creator-debugging.html of the "Qt Creator Manual":http://doc.qt.nokia.com/qtcreator-2.4/index.html.

vincegata

If it was that easy I wouldn't be posting this question here :)

In Locals and Expressions window I do have readline variable, it has a triangle, but if I click on it, it expands just nothing. I took a screenshot but I do not see how to post it here.

[quote author="Volker" date="1327698555"]Just set a breakpoint at the line of interest. The "locals and expressions" tab of the debugger lists all variables in the current method, including the this pointer. Your readline variable should show up there. It also should have a + signe or a triangle the left, you can expand it and it shows you the contents of the array then. If you use a char * instead, it is treated as a string and the string is displayed directly.

Find more infos about the debugger in the "respective section":http://doc.qt.nokia.com/qtcreator-2.4/creator-debugging.html of the "Qt Creator Manual":http://doc.qt.nokia.com/qtcreator-2.4/index.html.[/quote]

goetz

On DevNet, you cannot uplaod images directly. Just use a storage provider of your choice (dropbox, flickr, picasaweb, etc. are popular).

In my case, if I just put a

@
char rl[16];
@

The debugger shows this (I'm using Creator 2.4 on a Mac):

!http://qdn.berlinbikerx.de/Creator-Debugger-char-array.png!

vincegata

I do not have that :(

What I have is:

goetz

The image is not protected, maybe some setting needs to be tweaked to make it public.

vincegata

Please check this one:

goetz

Hm, what makes me wonder is that the type is char[] in your screenshot, whereas in mine it's char[16]. How did you declare that variable?

vincegata

ah, good catch. However it's still a bug if it's not resolvable through some sort of setting.

So, if I declare it the following way then I cannot see the content:
int MAXLINE = 1024;
char sendline[MAXLINE], recvline[MAXLINE];

It shows the variable if I declare:
char sendline [1024], recvline [1024];

Any ideas how to resolve it?

goetz

I'm not 100% sure here, but I would say that allocating a static array on the stack using dynamically calculated array size, i.e. putting a variable between the brackets, is not supported by all compilers. But that's a topic for the "C++ Gurus Forum":/forums/viewforum/36/

Regarding Qt Creator: I would guess that it's plain just not supported here. The code model would need to know the size of the array, but that is only calculated during runtime. Creator would have to evaluate the value of the MAXLINE variable and use that for the display of the array.

vincegata

Thank you for your help!