Generate an unambiguous random string from a set of possible characters.

unambiguous-random-string.php

<?php

/**
 * Generate an unambiguous random string from a set of possible characters.
 *
 * The range of possible characters is taken from [a-z] and [0-9] with
 * some removed to remove ambiguity if read aloud.
 *
 * Removed as they’re visually similar:
 *
 * l,1
 * o,0
 * s,5
 * u,v
 * z,2
 *
 * Removed as they’re phoentically similar:
 *
 * m,n
 * f,s
 */
function randomString($length = 8)
{
    $possibleChars = 'abcdeghijkpqrtwxy346789';
    $token = '';
    while(strlen($token) < $length) {
        $token .= $possibleChars[rand(0, strlen($possibleChars) -1)];
    }
    return $token;
}

echo randomString(3);