how to print a function's return value

how to print a function's return value

[Tom Frank]

hi,

in source code , there is a fuction call like this :  int a = func(param);

then I debug it with gdb , whein it stop at this line,I want to print
the func's retvalue, which results  in a gdb sigtrap,and

cause gdb to go into a trap,  then I can not find where am I .

I konw there is a command to prevent gdb going to trap  like  this,
what is  that command?

thanks!

Re: how to print a function's return value

[Doug Evans]

On Wed, Jul 11, 2012 at 8:10 AM, Tom Frank <gdbhelper@gmail.com> wrote:
> hi,
>
> in source code , there is a fuction call like this :  int a = func(param);
>
> then I debug it with gdb , whein it stop at this line,I want to print
> the func's retvalue, which results  in a gdb sigtrap,and
>
> cause gdb to go into a trap,  then I can not find where am I .
>
> I konw there is a command to prevent gdb going to trap  like  this,
> what is  that command?

Hi.
Your question is a bit confusing.
If I were to set the sigtrap aside, there are two ways to print func's
return value.

#1
(gdb) print func(param)

IOW call func from gdb.  Depending on what func does this may or may
not be reasonable.

The second way is to either set a breakpoint on func or step into into
and then step out of it like this:

#2
(gdb) step   # step into func
(gdb) finish   # run until func returns, gdb will print its return value


Now, as for sigtrap, I think in order to provide an accurate answer I
need more details.  An example session log for example.