Text justifier

You are given a string and a width. Write a script to return the string that centers the text within that width using asterisks * as padding.

Examples

Example 1
Input: $str = 'Hi', $width = 5
Output: '*Hi**'
Text length = 2, Width = 5
Need 3 padding characters total
Left padding: 1 star, Right padding: 2 stars

Example 2
Input: $str = 'Code', $width = 10
Output: '***Code***'
Text length = 4, Width = 10
Need 6 padding characters total
Left padding: 3 stars, Right padding: 3 stars

Example 3
Input: $str = 'Hello', $width = 9
Output: '**Hello**'
Text length = 5, Width = 9
Need 4 padding characters total
Left padding: 2 stars, Right padding: 2 stars

Example 4
Input: $str = 'Perl', $width = 4
Output: 'Perl'
No padding needed

Example 5
Input: $str = 'A', $width = 7
Output: '***A***'
Text length = 1, Width = 7
Need 6 padding characters total
Left padding: 3 stars, Right padding: 3 stars

Example 6
Input: $str = '', $width = 5
Output: '*****'
Text length = 0, Width = 5
Entire output is padding

Analysis

This is not a hard challenge, and as in many previous ones it can probably be done with a single rather impenetrable regular expression. I'll leave that for others to do.

I took the simple approach of calculating the number of asterisks required:

$asterisks = $width - length($string);

and then concatenating

• int($asterisks / 2) asterisks
• the input string
• ($asterisks - int($asterisks / 2)) asterisks.

That copes with all the edge cases such as an empty string, a zero $width with an empty string, and a string with just one fewer characters than $width.

And lastly I retun an error message if $string is longer than $width.

The post presents the Text Justifier and Word Sorter tasks clearly with well-explained inputs and desired outputs, giving readers a solid grounding in the problem definitions. The examples are practical and show the expected string centering and alphabetical ordering behavior in a way that supports straightforward implementation.

This review may cover either or both challenges for this week.

I am sorry that the 'Try it' feature is currently working very slowly or not at all owing to some issue with my web hosting provider.

Try it 

Try running the script with any input:

Your $string =

example: mouse-trap

Your $width =

example: 14

⤡

#!/usr/bin/perl

# Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge

use v5.26;    # The Weekly Challenge - 2026-02-09
use utf8;     # Week 360 - task 1 - Text justifier
use warnings; # Peter Campbell Smith
binmode STDOUT, ':utf8';
use Encode;

text_justifier('Code', 10);
text_justifier('Toad', 11);
text_justifier('Road', 4);
text_justifier('Mode', 20);
text_justifier('Node', 21);
text_justifier('Bode', 5);
text_justifier('', 1);
text_justifier('', 0);

sub text_justifier {
    
    my ($string, $width, $length, $asterisks, $left, $output);
    
    # initialise
    ($string, $width) = @_;
    say qq[\nInput:  \$string = '$string', \$width = $width];
    
    # how many asterisks?
    $asterisks = $width - length($string);
    
    # we can do it
    if ($asterisks >= 0) {
        $left = int($asterisks / 2);
        say qq[Output: ] . ('*' x $left) . $string . ('*' x ($asterisks - $left));
        
    # but not if the string won't fit
    } else {
        say qq[Output: Error: string is longer than width];
    }
}

10 lines of code

Output from script

Input:  $string = 'Code', $width = 10
Output: ***Code***

Input:  $string = 'Toad', $width = 11
Output: ***Toad****

Input:  $string = 'Road', $width = 4
Output: Road

Input:  $string = 'Mode', $width = 20
Output: ********Mode********

Input:  $string = 'Node', $width = 21
Output: ********Node*********

Input:  $string = 'Bode', $width = 5
Output: Bode*

Input:  $string = '', $width = 1
Output: *

Input:  $string = '', $width = 0
Output: