Percentage of character

You are given a string, $str and a character $char. Write a script to return the percentage, nearest whole, of the given character in the given string.

Examples

Example 1
Input: $str = "perl", $char = "e"
Output: 25

Example 2
Input: $str = "java", $char = "a"
Output: 50

Example 3
Input: $str = "python", $char = "m"
Output: 0

Example 4
Input: $str = "ada", $char = "a"
Output: 67

Example 5
Input: $str = "ballerina", $char = "l"
Output: 22

Example 6
Input: $str = "analitik", $char = "k"
Output: 13

Analysis

What's needed is a fraction. The denominator is just length($str) and the numerator can be found by doing

$chars = $str;
$chars =~ s|[^$char]+||g;

whereupon length($chars) is the desired number.

All that remains is to divide one by the other, add 0.5 (to get the nearest percentage) and discard the fractional part.

I had hoped to be able to count the the number of $char by using

$count = ($str =~ y|$char|$char|)

but unfortunately that doesn't work because Perl doesn't evaluate $char in a transliteration: it treats '$char' as a literal string and counts the number of '$', 'c', 'h', 'a' and 'r'.

Perl pure regex implementation to deal with both tasks. Don't forget to try DIY tool.

Try it 

Try running the script with any input:

Your $str =

example: abracadabra is a magic spell

Your $char =

example: a

⤡

#!/usr/bin/perl

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

use v5.26;    # The Weekly Challenge - 2024-06-10
use utf8;     # Week 273 - task 1 - Percentage of character
use warnings; # Peter Campbell Smith
binmode STDOUT, ':utf8';

percentage_of_character('the cat sat on the mat', 'a');
percentage_of_character('percentage of character', 'g');
percentage_of_character('the weekly challenge', 'z');
percentage_of_character('zzzzzzzzzzzzzzzzzz', 'z');

sub percentage_of_character {
    
    my ($str, $char, $chars);
    
    # remove $char from $str
    ($str, $char) = @_;
    $chars = $str;
    $chars =~ s|[^$char]+||g;
    
    say qq[\nInput:  \$str = '$str', \$char = '$char'];
    say qq[Output: ] . int(length($chars) / length($str) * 100 + 0.5);
}

7 lines of code

Output from script

Input:  $str = 'the cat sat on the mat', $char = 'a'
Output: 14

Input:  $str = 'percentage of character', $char = 'g'
Output: 4

Input:  $str = 'the weekly challenge', $char = 'z'
Output: 0

Input:  $str = 'zzzzzzzzzzzzzzzzzz', $char = 'z'
Output: 100