Interpolate a constant (not variable) into 'heredoc'

Question

Consider:

<?php
   define('my_const', 100);
   echo <<<MYECHO
      <p>The value of my_const is {my_const}.</p>
MYECHO;
?>

If I put a variable inside the braces, it prints out. But not the constant. How can I do it?

Answer 1

Use sprintf()

define('my_const', 100);
$string = <<< heredoc
      <p>The value of my_const is %s.</p>
heredoc;

$string = sprintf($string, my_const);