Open src/Negative.php

<?php
  function show($x) {
    print "<tr><td>" . $x . "<td>" . -$x . "\n";
  }

  print "<table border>\n";
  print "<tr><td>X<td>-X\n";

  show(123456789);
  show(PHP_INT_MAX);
  show(-PHP_INT_MAX-1);

  print "</table>\n";
?>