operator precedence

drag0n

I am a newbie learning PHP and I got to the part about looping in PHP. I understand most of the script I have below but the only part I do not get is the "$distance += 50;" What does it mean? I know it is called the "operator precedence", but I do not understand what it means, in the book, it only says the Associativity of that is "left".
Thanks for any help you can give =)

<html>
<body>
<table border = 0 cellpadding = 3>
<tr>
  <td bgcolor = "#CCCCCC" align = center>Distance</td>
  <td bgcolor = "#CCCCCC" align = center>Cost</td>
</tr>
<? 
$distance = 50;
while ($distance <= 250 )
{
  echo "<tr>\n  <td align = right>$distance</td>\n";
  echo "  <td align = right>". $distance / 10 ."</td>\n</tr>\n";
  $distance += 50;
}
?>
</table>
</body>
</html>

cgraz

$distance += 50;

adds 50 to the distance variable. For example

<?

$distance = 100;

$distance += 50;

echo $distance;

?>

Would output 150. Likewise

$distance -= 50;

would subtract 50 from the distance variable.

Cgraz

drag0n

why do they need the = sign? Thanks

cgraz

Well there are two ways you could do this

$distance = $distance + 50;

$distance += 50;

The second way saves you from having to write $distance twice.

Cgraz

drag0n

Thanks that helped me alot, Im glad there are experts here to help me when Im in need or Ill never get past the fiurst chaptor.
Cheers!