Why am I getting 'Substitution replacement not terminated`' in my regex to replace C style comments?

Question

Trying to remove C-style comments and their delimiters. Seems straightforward but I'm spinning wheels. This is what I am trying:

$code =~ s/\/\*.+\*\//g;

However, the error I get is:

Substitution replacement not terminated

What to do?

Answer 1

Substitution replacements take the form:

s/FIND/REPLACE/FLAGS

Note that the delimiters can be any of many characters. Therefore when dealing with patterns that include slashes, it is often better to use a different delimiter, say #.

Your substitution replacement here is missing the replace section. This is perhaps clearer if we use # instead of / as a delimiter:

$code =~ s#\/\*.+\*\/#g;

What you are probably intending to use is:

$code =~ s/\/\*.+\*\///g;

Or for clarity,

$code =~ s#/\*.+\*/##g;

Note that since # is being used as a delimiter instead, it is no longer necessary to escape /.

Answer 2

You meant to write $code =~ s/\/\*.+\*\///g;

You don't have to use leaning toothpicks in your patterns:

$code =~ s{ /[*] .+ [*]/ }{}gx;

Although, you'll probably realize that this does not handle all possibilities well. For that, see How can I strip multiline C comments from a file using Perl?

Answer 3

Per this thread, the following worked:

$code =~ s#/\*.*?\*/##sg;