Backward Incompatible Changes
Although most existing PHP 5 code should work without changes, please take
note of some backward incompatible changes:
-
Safe mode is no
longer supported. Any applications that rely on safe mode may need
adjustment, in terms of security.
-
Magic quotes has been removed. Applications relying
on this feature may need to be updated, to avoid security issues.
get_magic_quotes_gpc() and get_magic_quotes_runtime()
now always return
FALSE. set_magic_quotes_runtime() raises an
E_CORE_ERROR level error on trying to enable Magic quotes.
-
The register_globals and
register_long_arrays php.ini directives
have been removed.
-
The mbstring.script_encoding directive has been removed. Use zend.script_encoding instead.
-
Call-time pass by reference has been removed.
-
The break
and continue
statements no longer accept variable arguments (e.g., break 1 + foo() * $bar;).
Static arguments still work, such as break 2;. As a side effect of this change
break 0; and continue 0; are no longer allowed.
-
In the date and time extension, the timezone can no longer be
set using the TZ environment variable. Instead you have to specify a timezone using the
date.timezone php.ini option or date_default_timezone_set()
function. PHP will no longer attempt to guess the timezone, and will instead fall back to "UTC" and issue
a
E_WARNING.
-
Non-numeric string offsets - e.g. $a['foo'] where $a is a string - now return
false on isset() and true on empty(), and produce a
E_WARNING
if you try to use them. Offsets of types double, bool and null produce a E_NOTICE. Numeric strings
(e.g. $a['2']) still work as before. Note that offsets like '12.3'
and '5 foobar' are considered non-numeric and produce a E_WARNING, but are converted
to 12 and 5 respectively, for backward compatibility reasons.
Note: Following code returns different result.
$str='abc';var_dump(isset($str['x'])); // false for PHP 5.4 or later, but true for 5.3 or less
-
Converting an array to a string will now generate an
E_NOTICE level
error, but the result of the cast will still be the string "Array".
-
Turning
NULL, FALSE, or an empty string into an object by adding a property
will now emit an E_WARNING level error, instead of E_STRICT.
-
Parameter names that shadow super globals now cause a fatal error. This prohibits code like
function foo($_GET, $_POST) {}.
-
The Salsa10 and Salsa20 hash algorithms have been removed.
-
The Tiger hash algorithm now uses big-endian byte ordering.
Please follow this example to write code that
is compatible with both PHP 5.3 and 5.4.
-
array_combine() now returns array() instead of
FALSE
when two empty arrays are provided as parameters.
-
If you use htmlentities() with asian character sets, it
works like htmlspecialchars() - this has always been the
case in previous versions of PHP, but now an
E_STRICT
level error is emitted.
-
The third parameter of ob_start() has changed from
boolean
erase to integer
flags. Note that code that explicitly set
erase to FALSE will no longer behave as expected
in PHP 5.4: please follow
this example to write
code that is compatible with PHP 5.3 and 5.4.
The following keywords are now reserved, and may not be used
as names by functions, classes, etc.
The following functions have been removed from PHP: