<?
# http://..../intro04.php
# http://..../intro04.php?myvar=10
if (empty($myvar) or $myvar < 1 or $myvar > 10) { $myvar = 5; }
$i = 1;
while ($i <= $myvar) {
  echo "$i<br>";
  $i++;
}
echo "<hr>";  # =====
$char = array("a","b","c","d","e","f","g","h","i","j");
echo "<ol>";
$i = 0;
do {
  echo "<li>$char[$i]";
  $i++;
} while ($i < $myvar);
echo "</ol>";
?>