Regex for matching over 2 lines

[svendok]

Hi,
I have thousands of lines of code like this:

Blah1 blah1 blah1 = A1;
Yada1 yada1 yada1 = B1;
Blah2 blah2 blah2 = A2;
Yada2 yada2 yada2 = B2;

I want to swap the A value with the B value.

What is the syntax for a Perl regex that would do this? I'm struggling with the line break.

Thanks in advance.

svend

[Rabbit]

Assuming you have multi-line turned on, \r\n represents a line break in windows while \n represents a line break in unix.

[svendok]

Thank you! I can't believe I forgot that...

So I guess the patterns would be:
Search:

(.*) = (.*)\r\n(.*) = (.*)

Replace:

$1 = $4\r\n$3 = $2

[Rabbit]

If you have trouble with the "." you may want to try ([^\r\n]*)

[miller]

perl automatically treats \n as \r\n internally on windows machines, so it is unnecessary to do that. At most, you might need to do \r?\n if you're working with files cross platform, but I wouldn't expect that you are.

Anyway, here's a script that switches the values of every odd and even line:

use strict;

my $data = do {local $/; <DATA>};

$data =~ s{(.*?) = (.*?)\n(.*?) = (.*?)\n}{$1 = $4\n$3 = $2\n}g;

print $data;

__DATA__
Blah1 blah1 blah1 = A1;
Yada1 yada1 yada1 = B1;
Blah2 blah2 blah2 = A2;
Yada2 yada2 yada2 = B2;
Blah3 blah3 blah3 = A3;
Yada3 yada3 yada3 = B3;

[svendok]

Thanks, Miller, that's very helpful! Didn't know that about Perl and Windows line breaks.