Tool to remove obsolete #ifdef statements from a C program?

corp1126 · 12-17-2009, 07:35 AM

Dear all,

I have an old C program that has some #ifdef foo statements which are defined in every build of the program. Since it would be exactly the same if they were there or not I'd like to get rid of them to make things easier to look at. The problem is that there are rather a lot of them, does anyone know of a pre-existing tool to remove all the #ifdef foo statements and their associated #elif, #else and #endif lines?

I could script this myself but don't want to waste the effort if a tool already exists!

Many thanks.

smeezekitty · 12-18-2009, 02:28 AM

you could write a program to do it:

Code:

-psudeo code-
file1 = open inputfile read
file2 = open outputfile write
while not end-of-file file1
getline from file1 into buffer
compare buffer with #ifdef,#else,#endif
if buffer not = #ifdef,#else,#endif then
write buffer to file2
while end
close file1,file2
return

ta0kira · 12-18-2009, 02:53 AM

What smeezekitty said, but with sed or awk.
Kevin Barry

ghostdog74 · 12-18-2009, 05:47 AM

simple example

Code:

$ more file
1 text i want
#ifdef <token>
 code
#else
 code
#endif
2 text i want
3 text i want
#ifdef <token>
 code
#else
 code
#endif

$ awk -vf=0 '/#endif/{f=0;next}/#ifdef/{f=1}f==0' file
1 text i want
2 text i want
3 text i want

gnashley · 12-19-2009, 09:10 AM

If I understood correctly, the OP wants to keep the code contained in the ifdefs -he just wants to eliminate the ifdef statements.
If he wants to eliminate both the ifdef statements and the code they contain, then he could use 'unfidef' which is part of the linux kernel sources, or available separately.

ta0kira · 12-19-2009, 03:57 PM

Quote:

Originally Posted by ghostdog74

simple example

Code:

$ more file
1 text i want
#ifdef <token>
 code
#else
 code
#endif
2 text i want
3 text i want
#ifdef <token>
 code
#else
 code
#endif

$ awk -vf=0 '/#endif/{f=0;next}/#ifdef/{f=1}f==0' file
1 text i want
2 text i want
3 text i want

You need to keep one condition or the other; eliminating both changes the code. There should be a line that says "code" still, whether it be the first or the second.
Kevin Barry

ta0kira · 12-19-2009, 04:00 PM

You might check to see if Eclipse has some refactoring tool to do this for you (though I recommended command-line before) so that context, etc. can be taken into account.
Kevin Barry

sundialsvcs · 12-21-2009, 08:34 PM

I'd suggest leaving well enough alone.

tuxdev · 12-21-2009, 08:37 PM

Whenever I'm tasked with this kind of cleanup work, I just sit down with a good editor (Vim!) and crank through it one file at a time.