Weeding out comments is not as easy as you might think:

println( "This starts a comment? // Or does it\n" ); <== match ?

// /*
print( "*/ What happens now ?\n" ); <== match ??
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You will need a parser for your language that understands the basics of that language at least well enough to know when the "comment starter markers" are within a string and when they actually apply. There is Text::Balanced and Regexp::Common, which have prefabricated regexes that attempt this task, and if they are not suitable for the language you are trying to parse, Parse::RecDescent or Parse::YAPP can be used to write your own parser.