<?php
$array = array(
    'fruit1' => 'apple',
    'fruit2' => 'orange',
    'fruit3' => 'grape',
    'fruit4' => 'apple',
    'fruit5' => 'apple');

// this cycle echoes all associative array
// key where value equals "apple"
while ($fruit_name = current($array)) {
    if ($fruit_name == 'apple') {
        echo key($array), "\n";
    }
    next($array);
}
?>

<?php
function getFileExtension($file) {
    return end(explode(".", $file));
}
?>

<?php

function uniqidReal($length = 8) {
    // uniqid gives 8 chars, can be changed
    if (function_exists("random_bytes")) {
        $bytes = random_bytes(ceil($length / 2));
    } elseif (function_exists("openssl_random_pseudo_bytes")) {
        $bytes = openssl_random_pseudo_bytes(ceil($length / 2));
    } else {
        throw new Exception("no cryptographically secure random function available");
    }
    return substr(bin2hex($bytes), 0, $length);
}

/*
//for testing
for($i = 0; $i < 10; $i++) {
  echo "<br>";
  echo uniqidReal();
}
*/
?>

<?php
function getRandomId($min = NULL, $max = NULL) {
    if (is_numeric($min) && is_numeric($max)) {
        return mt_rand($min, $max);
    }
    else {
        return mt_rand();
    }
}
?>

<?php
$im = imagecreatefrompng('example.png');
$size = min(imagesx($im), imagesy($im));
$im2 = imagecrop($im, ['x' => 0, 'y' => 0, 'width' => $size, 'height' => $size]);
if ($im2 !== FALSE) {
    imagepng($im2, 'example-cropped.png');
    imagedestroy($im2);
}
imagedestroy($im);
?>

<?php
$username = "Austin Leath -_#";
$username_err = "no error";
if(preg_match('/[^a-z_\-0-9]/i', $string)) {
  $username_err = "Username can only contain alphanumeric characters, dashes, and underscores.";
}

echo $username_err
?>