PHP 3 and 4 Incompatibilities: A Closer Look Continued

Inc. #2 - in PHP 4, multiple calls to setcookie() are performed in the order called

This setcookie() behavior is opposite that of PHP 3, in which calls to setcookie() were executed in reverse call order. This will be most important when you want to make sure you've deleted one cookie before inserting another. Say, for example, you've already (or might have already) set 19 cookies for a user from one particular server. If you try to set 2 more, theoretically, the user's browser may delete the oldest cookie you've given it (according to Netscape's cookie specification) rather than hold more than 20 cookies from your server. If you'd rather clear out some specific cookies before inserting, you could do this in PHP 3:

  setcookie ("NewCookie2", $cookie_val2,time()+3600);
  setcookie ("NewCookie1", $cookie_val1,time()+3600);
  setcookie ("OldCookie2");
  setcookie ("OldCookie1");

In PHP 4, you'd need to send the commands in reverse (or correct, depending on how you look at it) order for the same effect:

  setcookie ("OldCookie1");
  setcookie ("OldCookie2");
  setcookie ("NewCookie1", $cookie_val1,time()+3600);
  setcookie ("NewCookie2", $cookie_val2,time()+3600);

Probably not a problem, unless you and your coworkers are going crazy with setting cookies...

Inc. #3 - {$ is not supported within encapsulated strings

  print "{$x}";
    or
  print "{$ }";

The content you're printing to a user's browser usually won't use bracketed variables; but if you generate your cascading style sheets or javascript functions with PHP you might have problems. For example, if you change the color of H1 tags based on some user-supplied or other variable:

  <style type="text/css">
  <!--
  H1
  <?PHP
    Function user_css ($some_var) {
      if ($some_var == 'r') {
        return "color: red";
      }
      else {
        return "color: blue";
      }
    }
    $x = user_css ($some_var);
    print "{$x}";
  ?>
  -->
  </style>

  print "\{$x}";

  print "{" . $x . "}";

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