delete comments in .c file

[Timex]

I want to delete all comments in .c file.

Size of .c file is very big.

Any good idea to do this?

Please show me example code.

[Jem Berkes]

> I want to delete all comments in .c file.

Size of .c file is very big.

Any good idea to do this?

Assuming you have C comments /* like this, right? */
You can use UNIX sed (stream editor). You're not going to believe this,
but: cat input.c | sed -e 's/\/\*.*\*\///g' > output.c

Do a diff to make sure it's working correctly.

--
Jem Berkes
http://www.sysdesign.ca/

[Ed Morton]

Jem Berkes wrote:

I want to delete all comments in .c file.

Size of .c file is very big.

Any good idea to do this?

Assuming you have C comments /* like this, right? */
You can use UNIX sed (stream editor). You're not going to believe this,
but: cat input.c | sed -e 's/\/\*.*\*\///g' > output.c

Do a diff to make sure it's working correctly.

That would only work if all comments are in the form you describe, which
isn't likely. e.g. it won't work if the comments are:

/* Start of a fairly common form
* of comment block.
*/

or:

/* set x: */ x = 7; /* now more stuff... */

In the first case it won't delete the comment while in the second
unusual case it'll delete both the comments plus the "x = 7;" assignment
between them.

You need to Google around or if you want a UNIX tool solution, post this
to a UNIX NG (e.g. comp.unix.quest ions or comp.unix.shell ).

Ed.

[Keith Thompson]

Jem Berkes <je*@users.pc9_ _org> writes:

I want to delete all comments in .c file.

Size of .c file is very big.

Any good idea to do this?

Assuming you have C comments /* like this, right? */
You can use UNIX sed (stream editor). You're not going to believe this,
but: cat input.c | sed -e 's/\/\*.*\*\///g' > output.c

Do a diff to make sure it's working correctly.

That won't detect multi-line comments. It also fails to properly
ignore comment delimiters inside string and character literals. It
deletes everything from the first "/*" on a line to the last "*/" on
the same line; for example, it transforms this:
x = /* one comment */ 42; /* another comment */
to this:
x =
And it replaces each comment by nothing rather than by a blank, so the
following valid C fragment:
x = sizeof/*comment*/int;
is replaced with this:
x = sizeofint;

If you're dealing with C99 code you'll have to worry about "//"
comments (many pre-C99 compilers support these as an extension).

Stripping C comments is a lot more complex than it looks; you almost
have to duplicate most of the functionality of the preprocessor to get
it right.

I really have to ask the original poster: why do you want to do this?

--
Keith Thompson (The_Other_Keit h) ks*@cts.com <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://www.sdsc.edu/~kst>
Schroedinger does Shakespeare: "To be *and* not to be"

[Derk Gwen]

"Timex" <su********@hot mail.com> wrote:
# I want to delete all comments in .c file.
#
# Size of .c file is very big.
#
# Any good idea to do this?
#
# Please show me example code.

tclsh <<':eof'
set c [open something.c]
set b [read $c]
close $c

regsub -all {//[^\n]*\n} $b \n b
regsub -all {/[*]([^*]|[*](?!/))*[*]/} $b {} b

set c [open something-1.c w]
puts $c $b
close $c
:eof

--
Derk Gwen http://derkgwen.250free.com/html/index.html
The whole world's against us.

[Keith Thompson]

Derk Gwen <de******@HotPO P.com> writes:

"Timex" <su********@hot mail.com> wrote:
# I want to delete all comments in .c file.
#
# Size of .c file is very big.
#
# Any good idea to do this?
#
# Please show me example code.

tclsh <<':eof'
set c [open something.c]
set b [read $c]
close $c

regsub -all {//[^\n]*\n} $b \n b
regsub -all {/[*]([^*]|[*](?!/))*[*]/} $b {} b

set c [open something-1.c w]
puts $c $b
close $c
:eof

This seems to add an extra blank line at the end of the output file.
It transforms "token/**/pasting" to "tokenpasti ng", which doesn't
violate the original poster's requirements, but it doesn't match the
way comments are treated in C.

It also doesn't ignore comment delimiters in string and character
literals.

--
Keith Thompson (The_Other_Keit h) ks*@cts.com <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://www.sdsc.edu/~kst>
Schroedinger does Shakespeare: "To be *and* not to be"

[Colin Newell]

Assuming you have access to the C preprocessor (cpp) you can do a quick hack
to use that. Isolate the file from it's include files and run like,

cpp -nostdinc file.c > new_file.c

It should warn that it cannot find all the include files. Now put your
#includes back in and you should have a comment free file.

This is a quick and dirty solution because the C preprocessor is trying to
do a whole load of stuff aswell as stripping comments. You need to make
sure that there are no #defines because otherwise they will be expanded out.
Put them back in after you have run the processor.

I have only come across the C preprocessor as a seperate program called
'cpp' on *nix boxes. It may be available on windows but I do not know where
or how.
Colin.

"Timex" <su********@hot mail.com> wrote in message
news:bn******** **@news.kreonet .re.kr...

I want to delete all comments in .c file.

Size of .c file is very big.

Any good idea to do this?

Please show me example code.

[Tim Hagan]

Timex wrote:

I want to delete all comments in .c file.

Size of .c file is very big.

Any good idea to do this?

Please show me example code.

This will replace each /* ... */ style comment with a single space:

#include<stdio. h>
int main(void){i\
nt c,p=-1,k=0,s=0
;while((c=getch ar
())!=EOF){if(s= =0
){if(p=='/'&&c==
'*'){s=1;k=2;}e l\
se if(c=='\"'&&p
!='\\'&&p!='\'' )s
=2;}else if(s==1)
{if (p=='*'&&c==
'/')s=0;}else if(
s==2){if(c=='\" '
&&p!='\\')s=0;} if
(k==1)putchar(' '
);if(p>0&&s!=1) {
if(!k)putchar(p );
if(--k<0)k=0;}p=c
;}putchar(p);re t\
urn 0;}

--
Tim Hagan

[Jeremy Yallop]

Tim Hagan wrote:

This will replace each /* ... */ style comment with a single space:

#include<stdio. h>
int main(void){i\
nt c,p=-1,k=0,s=0
;while((c=getch ar
())!=EOF){if(s= =0
){if(p=='/'&&c==
'*'){s=1;k=2;}e l\
se if(c=='\"'&&p
!='\\'&&p!='\'' )s
=2;}else if(s==1)
{if (p=='*'&&c==
'/')s=0;}else if(
s==2){if(c=='\" '
&&p!='\\')s=0;} if
(k==1)putchar(' '
);if(p>0&&s!=1) {
if(!k)putchar(p );
if(--k<0)k=0;}p=c
;}putchar(p);re t\
urn 0;}

It doesn't handle line-splicing. Also, putchar(-1) is not portable.

Jeremy.

[Halleyscomet]

> I want to delete all comments in .c file.

Size of .c file is very big.

You work for SCO's Linux division, don't you?