- var_dump: documentation ( source)
<?php
echo "null != 'string' -> ";
var_dump(null != 'string');
echo "<br />";
echo "false != 'string' -> ";
var_dump(false != 'string');
echo "<br />";
echo "0 != 'string' -> ";
var_dump(0 != 'string');
echo "<br />";
echo "1 != 'string' -> ";
var_dump(1 != 'string');