- substr: documentation ( source)
- base64_decode: documentation ( source)
- explode: documentation ( source)
<?php
$student_comment_new = 'PDE+PEwuSW50cm9kdWN0aW9uIC0gUGFnZSAxIG9mIDI+TVkgUFJFVEVORCBTRUNPTkQgPGUuMT4=';
$fixed = base64_decode($student_comment_new);
echo $fixed . "\n\n";
//Decode the entire comment
$comment_cltxt = base64_decode($student_comment_new);
echo $comment_cltxt . "\n\n";
//get the comment number.
$comment_nr = explode('><L.', $comment_cltxt)[0];
$comment_nr = explode('<', $comment_nr)[1];
//get the comment end-text
$comment_nr_string = '<' . $comment_nr . '>';
$comment_end_string = '<e.' . $comment_nr . '>';
echo $comment_nr . "\n";
echo $comment_nr_string . "\n";
echo $comment_end_string . "\n";
//get the comment text itself
$pos1 = strlen($comment_nr_string);
$pos2 = strlen($comment_end_string);
$comment_text = substr($comment_cltxt, $pos1, -$pos2);
echo $comment_text . "\n";