• Migrating from PHP 5.2.x to PHP
  • Backward Incompatible Changes

  • Backward Incompatible Changes
  • Backward Incompatible Changes

    Backward Incompatible Changes

    Although most existing PHP 5 code should work
    without changes, please take note of some backward incompatible

    • The newer internal
      parameter parsing API has been applied across all the extensions
      bundled with PHP 5.3.x. This parameter parsing API causes functions
      to return NULL when passed
      incompatible parameters. There are some exceptions to this rule,
      such as the get_class()
      function, which will continue to return
      FALSE on error.
    • clearstatcache() no longer clears the
      realpath cache by default.
    • realpath() is now fully platform-independent.
      Consequence of this is that invalid relative paths such as
      __FILE__ . “/../x” do not work anymore.
    • The call_user_func() family of functions now
      propagate $this even if the callee is a parent
    • The array functions
      natsort(), natcasesort(), usort(), uasort(),
      uksort(), array_flip(), and array_unique() no longer accept objects
      passed as arguments. To apply these functions to an object, cast
      the object to an array first.
    • The behaviour of
      functions with by-reference parameters called by value has changed.
      Where previously the function would accept the by-value argument, a
      fatal error is now emitted. Any previous code passing constants or
      literals to functions expecting references, will need altering to
      assign the value to a variable before calling the
    • The new mysqlnd library
      necessitates the use of MySQL 4.1’s newer 41-byte password format.
      Continued use of the old 16-byte passwords will cause mysql_connect() and similar functions to emit
      the error, “mysqlnd cannot connect to MySQL 4.1+ using old
    • The new mysqlnd library
      does not read mysql configuration files (my.cnf/my.ini), as the
      older libmysqlclient library does. If your code relies on settings
      in the configuration file, you can load it explicitly with the
      mysqli_options() function. Note that this
      means the PDO specific constants
      are not defined if MySQL support in PDO is compiled with
    • The trailing / has been
      removed from the SplFileInfo class and other related directory
    • The __toString() magic method can no longer accept
    • The magic methods
      __get(), __set(), __isset(), __unset(), and __call() must always be public and can no longer be
      static. Method signatures are now enforced.
    • The __call() magic method is now invoked on access to
      private and protected methods.
    • func_get_arg(), func_get_args() and func_num_args() can no longer be called from
      the outermost scope of a file that has been included by calling
      include or require from
      within a function in the calling file.
    • An emulation layer for
      the MHASH extension to wrap around the Hash extension have been
      added. However not all the algorithms are covered, notable the s2k
      hashing algorithm. This means that s2k hashing is no longer
      available as of PHP 5.3.0.

    The following keywords are now reserved and may
    not be used in function, class, etc. names.