<?php

/**
 * Function returns the total number of consonants present in the given
 * string using a linear search through the string
 *
 * @param string $string
 * @return int
 */
function countConsonants(string $string): Int
{
    if (empty($string)) {
        throw new \Exception('Please pass a non-empty string value');
    }

    $vowels     = ['a', 'e', 'i', 'o', 'u']; // Vowels Set
    $string     = strtolower($string); // For case-insensitive checking

    $consonantCount = 0;

    for ($i = 0; $i < strlen($string); $i++)
    {
      if (!in_array($string[$i], $vowels) &&
        $string[$i] >= 'a' && $string[$i] <= 'z')
        {
            $consonantCount++;
        }
    }

    return $consonantCount;
}