Re: Question regarding printing to terminal e.g. variable values etc.

On 1/10/2011 10:05 AM, Lana Eliason wrote:
> Hi all,
>
> I'm very new to the player/stage environment and am currently having a
> few issues. I am using stage 3.2.2 in Fedora 12.
>
> I'm trying to code some c++ for making one robot follow the other
> which is doing some odd things, hence I am trying to track what is
> going on. My initial thought is to get the code to print out the
> values of variables it is using, however the standard printf command
> e.g. printf("test"); ...which I have been recommended to use doesn't
> output anything. It seems it just skips over this line entirely. Can
> anybody please tell me why this might be and/or how else to output
> values?
>
> Also, is there any more newbie-friendly way of coding for
> player/stage? Currently i'm just using emacs and compiling it in the
> terminal - its not exactly as convenient to do as coding in say,
> Visual Studio which i'm used to... The lack of any form of debugging
> is proving a bit of a pain.
>
> Any advice would really be very much appreciated.
>
> Thank you :)
>
> Lana

Hello,

First off, are you trying to write a Player client to control your 
robots, or are you trying to write a Stage controller?  You only mention 
that you're using Stage.  Also, are you getting any error messages or 
other output?  The lack of output from printf could mean your program is 
never reaching the printf call, which could mean you have an error 
somewhere.  It could also mean that your program crashes before it 
flushes the output buffer, you can add a call to fflush(stdout); after 
each printf() to ensure everything you're sending to stdout will show 
up.  Without more information about your setup, it's hard to tell what 
exactly is going on.

The best way to debug your code is to use a tool like gdb.  Its command 
line interface isn't terribly friendly at first, but it's pretty 
powerful once you get to know it.  There are other options though: if 
you're into graphical IDE's, you might try installing Eclipse (su -c 
'yum install eclipse-cdt') and using its C/C++ development tools to 
create a C++ project to write your code.  Once you set up the include 
paths and libraries for your project to point to Player or Stage, you 
should be able to debug a player client from within Eclipse.  Eclipse 
has pretty good gdb integration, you can set breakpoints from within the 
editor, etc.  You could also go the emacs route and do everything from 
the emacs environment (code, gdb, gcc, etc.)  There are lots of emacs 
tutorials floating around on the net.

Rich

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