PHP serialization error with ' " counts as two characters - php

Question

I'm having problems with php serialization, when ever ' " are included i get an extra character space. Ex if it's 6 characters i get 7
$episodes_count = sizeof($episode_title);
$episodes = array();
$content = '';
for ($i = 0; $i <= $episodes_count; $i++) {
$title = htmlspecialchars($episode_title[$i], ENT_QUOTES);
$airdate = $episodes_airdates[$i];
$season = $episodes_seasons[$i];
$number = $episodes_numbers[$i];
$plot = $episodes_plot[$i];
// check if empty
if (!empty($title) && !empty($number ) && !empty($plot )) {
$episodes[] = array(
'title' => $title,
'airdate' => $airdate,
'season' => $season,
'number' => $number,
'plot' => $plot,
);
}
}
// Serialized Episodes in case they exist, if not, remove the goal post
if ( sizeof($episodes) > 0 ) {
$content = str_replace("'", '%',serialize($episodes));
}
update_post_meta($post_id, 'episodes', $content);
}

Answer 1

You pass some data that looks serialized to wordpress to update_post_meta - wordpress can have a problem with that and the data will get broken while stored and retrieved.
To prevent that, you can prefix the string so that it does not look serialized any longer or you even encode the whole string, e.g. with base64_encode. That will prevent wordpress and other components to modify the values due to encoding issues.