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Niti
#1 / 9
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 pattern matching across two lines I have text as follows:
foo^M
bar
in several files. I need to replace this with:
foobar
How can I match patterns across two lines?
Thanks,
Sent via Deja.com http://www.*-*-*.com/
Before you buy.
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Federico Abasca
#2 / 9
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pattern matching across two lines Quote:
> How can I match patterns across two lines?
Hello, the simplest way I see is:
while(<>) {
if(/patternA/) {
$_ = <>;
if(/patternB/) {
#You have detected the pattern accross two lines
}
}
Quote: }
I hope this helps,
Federico
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Rich Mor
#3 / 9
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pattern matching across two lines
Quote: > I have text as follows: > foo^M
> bar
> in several files. I need to replace this with:
> foobar
> How can I match patterns across two lines?
Mastering Regular Expressions ( Chapter 7 )
open(FH,$ARGV[0]);
local($/);
$str=<FH>;
close(FH);
$str =~ s/foo\r\nbar/foobar/gsm;
print $str;
--
=============================
Richard More
http://www.richmore.com/
Sent via Deja.com http://www.deja.com/
Before you buy.
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Ala Qumsie
#4 / 9
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pattern matching across two lines Quote:
> open(FH,$ARGV[0]);
It's better to check and see whether the open succeeded or not ..
Quote: > local($/);
why do you localize $_ when you don't use it?
Quote: > $str=<FH>; > close(FH); > $str =~ s/foo\r\nbar/foobar/gsm;
regexp making it match newlines. And the /m modifier affects the
behaviour of '^' and '$' making them match within a string.
You don't have a '.', '^' or '$' in your regexp, so why are you using
/sm?
--Ala
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Larry Rosle
#5 / 9
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pattern matching across two lines
Quote:
> > How can I match patterns across two lines?
> Hello, the simplest way I see is:
> while(<>) {
> if(/patternA/) {
> $_ = <>;
> if(/patternB/) {
> #You have detected the pattern accross two lines
> }
> }
> }
> I hope this helps,
Well, no, because in your code $_ still contains one line -- the second
one read. To match /patternB/ across two lines, you must concatenate,
not assign, to $_.
$_ .= <>;
--
(Just Another Larry) Rosler
Hewlett-Packard Laboratories
http://www.hpl.hp.com/personal/Larry_Rosler/
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Larry Rosle
#6 / 9
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pattern matching across two lines
Quote: ...
Quote: > > local($/); > why do you localize $_ when you don't use it?
it doesn't affect the rest of the program.
Quote: > > $str=<FH>; > > close(FH); > > $str =~ s/foo\r\nbar/foobar/gsm;
> Hmmm .. the /s modifier affects the behaviour of the dor '.' inside a
> regexp making it match newlines. And the /m modifier affects the
> behaviour of '^' and '$' making them match within a string.
> You don't have a '.', '^' or '$' in your regexp, so why are you using
> /sm?
character "\n", not the two characters "\r\n", even on systems where
"\r\n" is the external representation. (Excepting the use of binmode(),
of course, which would be wrong here.)
--
(Just Another Larry) Rosler
Hewlett-Packard Laboratories
http://www.hpl.hp.com/personal/Larry_Rosler/
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Ala Qumsie
#7 / 9
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pattern matching across two lines Quote:
> ...
> > > local($/);
> > why do you localize $_ when you don't use it?
> That is $/, not $_. The proper localization is in a block, though, so
> it doesn't affect the rest of the program.
Ooops!!! Perhaps I should start wearing glasses!
Thanks for catching that.
--Ala
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Abiga
#8 / 9
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pattern matching across two lines
<URL::">
&& >
&& > > How can I match patterns across two lines?
&& >
&& > Hello, the simplest way I see is:
&& > while(<>) {
&& > if(/patternA/) {
&& > $_ = <>;
&& > if(/patternB/) {
&& > #You have detected the pattern accross two lines
&& > }
&& > }
&& > }
&& >
&& > I hope this helps,
&&
&& Well, no, because in your code $_ still contains one line -- the second
&& one read. To match /patternB/ across two lines, you must concatenate,
&& not assign, to $_.
&&
&& $_ .= <>;
Of course, that's going to fail if line 1 matches patternA, and lines
2 and 3 combined match patternB.
Abigail
--
$; # A lone dollar?
=$"; # Pod?
$; # The return of the lone dollar?
{Just=>another=>Perl=>Hacker=>} # Bare block?
=$/; # More pod?
print%; # No right operand for %?
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| Wed, 18 Jun 1902 08:00:00 GMT |
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Bart Lateu
#9 / 9
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pattern matching across two lines Quote:
>Furthermore, the internal representation of newline is the single
>character "\n", not the two characters "\r\n", even on systems where
>"\r\n" is the external representation.
The OP didn't say what platform. He did say the input looked like:
foo^M
bar
This says to me:
* Unix
* CR is there.
You may want to make it optional:
s/(foo)\r?\n(bar)/$1$2/g;
Oh, I did some capturing just in case he wants a more generic text
matching than just literal foo's and bar's.
--
Bart.
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| Wed, 18 Jun 1902 08:00:00 GMT |
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