Word wrapping using a regex.

[Anonymous Monk]

Hi Monks!
I'm trying to have a word wrapping using a regex in Perl. What I would like is about every 50 characters or so to check for the next white-space occurrence and replace that space with a new line, and then do this for the whole string. I'd like to avoid looping one character at a time or using substr or placing the value into an array if possible. The code sample I have works, I'd like one's option and suggestion if there is a better way or a better regular expression to accomplish this.
Here is the code:

#!/usr/bin/perl -w

use strict;

my $string = 'I'm trying to have a word wrapping using a regex in Perl
+. What I would like is about every 50 characters 
or so to check for the next white-space occurrence and replace that sp
+ace with a newline, and then do this for the whole string. 
I'd like to avoid looping one character at a time or using substr or p
+lacing the value into an array if possible.
The code sample I have works, I'd like someone option and suggestion i
+s there a better way or better regular expression to accomplish this.
+';

$string =~ s/(.{1,50}\S|\S+)\s+/$1\n/mg;

print "$string\n";
exit;

Thanks for looking!

[MidLifeXis]

Would Text::Wrap be a reasonable solution, or must you use a regexp?

[Anonymous Monk]

Yeah, I have to use regexp!

[toolic]

Look at the regexes in the Text::Wrap source code:

perldoc -m Text::Wrap

[Anonymous Monk]

Smells like homework.

[TJPride]

Your regex is obviously not working properly, because it prints beyond the boundary of 50 characters. Here's another option:

use strict;
use warnings;

my $string = "I'm trying to have a word wrapping using a regex in Perl
+. What I would like is about every 50 characters  or so to check for 
+the next white-space occurrence and replace that space with a newline
+, and then do this for the whole string.  I'd like to avoid looping o
+ne character at a time or using substr or placing the value into an a
+rray if possible. The code sample I have works, I'd like someone opti
+on and suggestion is there a better way or better regular expression 
+to accomplish this.";

print '1234567890'x5 . "\n";
print wrap($string, 50) . "\n";

sub wrap {
    my ($s, $wrap) = @_;
    my (@lines, $line);
    
    while (length $s > $wrap) {
        ### Take one extra character so we can see if
        ### we're wrapping inside a word or not
        $line = substr($s, 0, $wrap+1);
        $line =~ s/\s+(\S*)$//;
        push @lines, $line;

        ### Add any word fragments back on
        $s = $1 . substr($s, $wrap);
        $s =~ s/^\s+//;
    }
    return join "\n", @lines;
}

[Additude]

I think to make this work we need to add another line at the end to tell it what to do with the last of the string that is less than $wrap.

sub wrap {
    my ($s, $wrap) = @_;
    my (@lines, $line);
    
    while (length $s > $wrap) {
        ### Take one extra character so we can see if
        ### we're wrapping inside a word or not
        $line = substr($s, 0, $wrap+1);
        $line =~ s/\s+(\S*)$//;
        push @lines, $line;

        ### Add any word fragments back on
        $s = $1 . substr($s, $wrap);
        $s =~ s/^\s+//;
    }
    push @lines, $s;  ##  Adds the the last of the $s string to @lines
    return join "\n", @lines;
}