if ($foo =~ m/(?:.{0,40}\n){0,4}/m) { print "ok" }

/m is for "multi-line" match

update: see bart below for why is this wrong . See sauoq answer instead.

update: now I've got it (I did learn something today!) :

The RE is:  /((?:[^\n]{0,40}\n){0,4})/

or:  /((?:.{0,40}\n){0,4})/     # thanks sauoq!

roughly meaning: group( (up-to-40 non-line-breaks, line-break) up-to-4 times)close-group

Test code:

$line = "x" x 38 . "\n";

sub test {
  ($res) = ($_[0] =~ /((?:[^\n]{0,40}\n){0,4})/);
  if ($res) {
     print "yes\n";
  }
  else {
     print "no\n";
  }
}

test( "x$line" x 4 );    # 39 x 4
test( "xx$line" x 4 );   # 40 x 4
test( "xxx$line" x 4 );  # 41 x 4
test( "xx$line" x 3 );   # 40 x 3
test( "x$line" x 5 );    # 39 x 5

[download]

output:

yes
yes
no
yes
yes

[download]

Thanks thelenm and BrowserUk. sauoq got something very similar too.

sauoq noted that  [^\n] is the same as a "dot".

In reply to Re: How do I match lines of 40 characters long in a block of text? by fglock
in thread How do I match lines of 40 characters long in a block of text? by kleinbiker7

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