Reverse a string correctly in PHP considering bytes, code points and graphemes

reverse-string.php

<?php

// For ASCII only
$hello = 'Hello';
$revStrBytes1 = '';
for ($i = strlen($hello) - 1; $i >= 0; $i--) {
    $revStrBytes1 .= $hello[$i];
}

// Alternative to the code above
$revStrBytes2 = strrev($hello);

// For multibyte string, but not combining code points
$cafe = 'Café';
$revStrCodePoints1 = '';
for ($i = mb_strlen($cafe) - 1; $i >= 0; $i--) {
    $revStrCodePoints1 .= mb_substr($cafe, $i, 1);
}

// Alternative to the code above
$codePointsCafe = mb_str_split($cafe);
$revStrCodePoints2 = implode('', array_reverse($codePointsCafe));

// For strings that combine code points, like emojis, etc
$flags = '🇧🇷 🇺🇸 🇯🇵';
$revStrGraphemes = '';
for ($i = grapheme_strlen($flags) - 1; $i >= 0; $i--) {
    $revStrGraphemes .= grapheme_substr($flags, $i, 1);
}

header('Content-Type: text/plain');
echo "$hello ←→ $revStrBytes1\n";
echo "$hello ←→ $revStrBytes2\n";
echo "$cafe ←→ $revStrCodePoints1\n";
echo "$cafe ←→ $revStrCodePoints2\n";
echo "$flags ←→ $revStrGraphemes\n";