mndoci has asked for the wisdom of the Perl Monks concerning the following question:

Hi Folks Have been looking around and have not seen a satisfactory answer for my problem. Which is as follows:

Say I have a text file which includes the following lines
----------------------
This line has a printf and is
multiline
This line has printf and is one line
This line will not be printed
----------------------

I want to print out every line with "printf" in it, but I want to report the multiline line completely, i.e the output should look like

This line has a printf and is
multiline
This line has printf and is one line

Could anyone suggest a solution?
Thank you

mndoci

"What you do in this world is a matter of no consequence. The question is, what can you make people believe that you have done?"-Sherlock Holmes in 'A study in scarlet'

Replies are listed 'Best First'.
Re: regex across multiple lines
by kvale (Monsignor) on Jun 28, 2002 at 05:34 UTC
    The first question is: what distinguishes a multiline from a single line in your text file? In your example, I see four separate lines, and only my knowledge of English allows me to associate "multiline" with the previous line. Regexes are powerful, but they don't speak English yet :)

    -Mark

[reply]

      Good question
      and therein lies the problem. I can't find any difference other than the inclusion of printf (which is always on the first line).

      mndoci

      "What you do in this world is a matter of no consequence. The question is, what can you make people believe that you have done?"-Sherlock Holmes in 'A study in scarlet'

[reply]
        Well, so how can you - as a human being - distinguish whether a line is part of a multiline. If you can't do that, then how should the computer be able to do it?

        -- Hofmator

[reply]
Re: regex across multiple lines
by frankus (Priest) on Jun 28, 2002 at 09:08 UTC 
    $/=undef;
$_=<DATA>;
s/([^\n]*printf.*?printf.*?\n)[^\n]*\n/$1/gs;
print;
__DATA__
This line has a printf and is
multiline
This line has printf and is one line
This line will not be printed

    [download]

    Based upon the test data provided, this works.
    Are we to assume that the multiline is a multiline printf function?,
    if so surely the line ends with a ';'?

    More information please.

    --

    Brother Frankus.

    ¤

[reply]
[d/l]

      You were quite right. That was the real problem and of course resolved in a similar way to what was suggested. I was curious about the possiblity of solving the problem if I had been provided a file with no ';'. It appears that the question in itself is unsound.

      Regards

      mndoci

      "What you do in this world is a matter of no consequence. The question is, what can you make people believe that you have done?"-Sherlock Holmes in 'A study in scarlet'

[reply]

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