使用highlight_string打印php代码

Question

I am trying to show my code with highlight_string. All of my variables are being stripped out of the printed code. What am I doing wrong? An example of what is happening ...

<?php highlight_string("
    <?
        $a=3;
        $b=4;
        if ($a < $b){
        echo 'a is less than b';
        }
    ?>"); 
?>

The output looks like this

    <?
        =3;
        =4;
        if ( < ){
        echo 'a is less than b';
        }
    ?>

Answer 1

Replace the double quotes (") with single quotes (') PHP tries to fill up variables printed within double quotes.

<?php highlight_string('
    <?
        $a=3;
        $b=4;
        if ($a < $b){
        echo \'a is less than b\';
        }
    ?>'); 
?>