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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.
  • The register_globals and register_long_arrays php.ini directives have been removed.
  • 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.
  • 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 following keywords are now reserved, and may not be used as names by functions, classes, etc.

The following functions have been removed from PHP:

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User Contributed Notes 6 notes

1 year ago
Missing some chars like german umlauts after use of htmlspecialchars? That's because the third param encoding has changed it's default value in PHP 5.4 from ISO-8859-1 to UTF-8.

Possible solution #1:
Change your code from this ...
<?php htmlspecialchars( 'äöü' ); ?>
... to this:
<?php htmlspecialchars ( 'äöü' , ENT_COMPAT | ENT_HTML401 , 'ISO-8859-1' ); ?>

Possible solution #2:
Create a wrapper function and replace htmlspecialchars( to i.e. isohtmlspecialchars( with your IDE/editor/shell...

Example of a wrapper function:
function isohtmlspecialchars( $str ){
htmlspecialchars ( $str , ENT_COMPAT | ENT_HTML401 , 'ISO-8859-1' );
anton at zebooka dot com
1 year ago
It seems that starting of PHP 5.4 you can not override class method with different signature.

class A
    public function
doSomething($a, $b)

B extends A
    public function

PHP Strict standards:  Declaration of B::doSomething() should be compatible with A::doSomething(B $a) in Command line code on line 1
the dot mail dot bg at gmail dot com
1 year ago
There should be samples given here. There are many ways to do such coversion:

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".
ky dot patterson at adlinkr dot com
1 month ago
If you have content that is not 100% UTF-8 then TAKE NOTE:

Starting in PHP 5.4 htmlspecialchars() and htmlentities() assume charset=UTF-8 by default AND WILL RETURN BLANK IF YOUR INPUT IS NOT VALID UTF-8.

So if you have a lot of function calls that look like this:
echo htmlspecialchars($input);
// or
echo htmlentities($input);
i.e. no charset and no flags -- and $input is ISO-8859 (or anything else apart from 7-bit ASCII or UTF-8) -- then PHP 5.4 and 5.5 will return an empty string, and you will be surprised and probably unhappy.

This is apparently a feature, not a bug.
luis at portanel dot com
1 year ago
It's not a PHP version incompatibility itself, but it's important to know that Microsoft dropped the php_mssql.dll support for the "mssql_" funcitions since this version.

To connect to a MSSQL database since 5.4, one good alternative are the PDO drivers.
blagdan at gmail dot com
7 months ago
'<?if'... worked in 5.3 as equivalent of '<?php if'... In 5.4 it's converted to '<!--?if'...
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