Text::Wrap does this.

use Text::Wrap;

$Text::Wrap::columns = 70;

print Text::Wrap::fill( '', '', join '', <DATA> );

__DATA__
This is a huge paragraph that no doubt spans quite a number of columns
+. My guess is that it may even span past 70 Columns, so we'll use the
+ nifty Text::Wrap module to limit the number of columns that this par
+agraph can take up to 70.
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You can use formats:

format =
^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ~~
$string
.
$string = get_some_really_long_string();
write;
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See perldoc perlform.

(Assuming you don't want paragraphs to wrap in the middle of words.)

Here's a nice little regex solution:

$paragraph =~ s/([^\n]{0,70})(?:\b\s*|\n)/$1\n/gi;
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my $max_width = 40;
$paragraph =~ s/([^\n]{0,$max_width})(?:\b\s*|\n)/$1\n/gio;
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Smart Substrings has some interesting insight. Combining that with the solution above:

$paragraph =~ s/([^\n]{50,70})(?:\b\s*|\n)/$1\n/gi;
while ( $paragraph =~ m/([^\n]{71})/ )
{
   $paragraph =~ s/([^\n]{70})([^\n])/$1\n$2/g;
}
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In other words, split lines which are more than 70 chars long and include no spaces. (Not sure the loop is necessary...)

It's not exactly clear what you're trying to do, but here are a couple of possibilities:

If you only want to show the first 70 characters of each line then read the lines in one at a line and use substr.

If you want to reformat the paragraphs so that they are no more that 70 characters wide, then read the whole paragraph in and reformat it using Text::Wrap.

Originally posted as a Categorized Answer.

$paragraph =~ s/([^\n]{50,70})(?:\b\s*|\n)/$1\n/gi;
while ($paragraph =~ m/([^\n]{71})/) {
  $paragraph =~ s/([^\n]{70})([^\n])/$1\n$2/g;
}
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cLive ;-)

^*When I was a kid, I was locked in my bedroom. I learnt English from an ABBA record. It was hard, but if I had to do the same again, I would my friend.

Fernando

- Milton Jones

Originally posted as a Categorized Answer.