* modifying gcc files and getting error
@ 2009-12-17 9:33 Wei Li
2009-12-17 9:48 ` John Graham
0 siblings, 1 reply; 2+ messages in thread
From: Wei Li @ 2009-12-17 9:33 UTC (permalink / raw)
To: gcc-help
Dear all:
I am trying to change some source files in the GCC compiler and
getting a compilation error.
In the file "gimple.h", I am adding
extern int x; // the x is global and should be accesable from other
files as well.
Then I called x in the "tree_into_ssa.c". However, when I compile the
gcc compiler using the make command I get the following massage:
undefined refernce to "x".
Any comments???
Thanks,
Abid
--
Regards,
Wei Li
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: modifying gcc files and getting error
2009-12-17 9:33 modifying gcc files and getting error Wei Li
@ 2009-12-17 9:48 ` John Graham
0 siblings, 0 replies; 2+ messages in thread
From: John Graham @ 2009-12-17 9:48 UTC (permalink / raw)
To: gcc-help
> I am trying to change some source files in the GCC compiler and
> getting a compilation error.
>
> In the file "gimple.h", I am adding
>
> extern int x; // the x is global and should be accesable from other
> files as well.
>
>
> Then I called x in the "tree_into_ssa.c". However, when I compile the
> gcc compiler using the make command I get the following massage:
>
> undefined refernce to "x".
>
>
> Any comments???
First, this is really a general programming question, and this mailing
list is more for gcc-specific issues. In future, try a general
programming forum like at
http://www.linuxquestions.org/questions/programming-9/.
This error occurs because "extern int x" declares a variable called x,
but does not define it - you need to define it (exactly once) with
"int x" in a source file that will be linked in with whatever source
files you want to use it in. If you don't know the difference between
declaring and defining a variable, I suggest you get a good C book and
have a thorough read.
John G
^ permalink raw reply [flat|nested] 2+ messages in thread
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