perl regexp to match bash comments

[roccivic]

Hi folks,

I'm having a really hard time writing what should be a really straightforward PERL regular expression. I need to match all comments in PNM and PGM image files. So I need to match strings that:


can start with anything
have a hash symbol '#'
are followed by any character except for '\n', '\r' or '\r\n'
are terminated by '\n', '\r' or '\r\n'


So far I tried this (which of course does not work)

$data = preg_replace( '/#./m', '', $data );

[Arndt]

Hi folks,

I'm having a really hard time writing what should be a really straightforward PERL regular expression. I need to match all comments in PNM and PGM image files. So I need to match strings that:


can start with anything
have a hash symbol '#'
are followed by any character except for '\n', '\r' or '\r\n'
are terminated by '\n', '\r' or '\r\n'


So far I tried this (which of course does not work)

$data = preg_replace( '/#./m', '', $data );

What about this?


$data = preg_replace( '/#.*/m', '', $data );

[roccivic]

What about this?


$data = preg_replace( '/#.*/m', '', $data );

It works great, thanks.

Was only one character away...

[shawnhcorey]

Hi folks,

I'm having a really hard time writing what should be a really straightforward PERL regular expression. I need to match all comments in PNM and PGM image files. So I need to match strings that:


can start with anything
have a hash symbol '#'
are followed by any character except for '\n', '\r' or '\r\n'
are terminated by '\n', '\r' or '\r\n'


So far I tried this (which of course does not work)

$data = preg_replace( '/#./m', '', $data );

Why are you asking for Perl and then write in PHP?

[roccivic]

That's cause PHP uses Perl Compatible Regular Expressions: http://www.php.net/manual/en/ref.pcre.php (as well as the deprecated POSIX regex).

[shawnhcorey]

That's cause PHP uses Perl Compatible Regular Expressions: http://www.php.net/manual/en/ref.pcre.php (as well as the deprecated POSIX regex).

OK, if you say so:

m{ \# [^\r\n] .*? (?: \r\n | \r | \n ) }msx;

[roccivic]

Your regexp also works great, although I had to strip the spaces and curly brackets:


$data = preg_replace( '/#[^\r\n].*?(?:\r\n|\r|\n)/m', '', $data );

Thanks ;)

[shawnhcorey]

Your regexp also works great, although I had to strip the spaces and curly brackets:

The curly brackets are delimiters. The /x option at the end allows whitespace in the pattern.