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1. strrpos() and strripos() now use the entire string as a needle. Be aware
that the existing scripts may no longer work as you expect.
EX :
Will give you different results. The former returns 3 while the latter
returns false rather than the position of the last occurrence of 'D'.
The same applies to strripos().
2. Illegal use of string offsets causes E_ERROR instead of E_WARNING.
EX :
$a = "foo";
Fatal error: Cannot use string offset as an array in ... on line 1
3. array_merge() was changed to accept only arrays. If a non-array variable is
passed, a E_WARNING will be thrown for every such parameter. Be careful
because your code may start emitting E_WARNING out of the blue.
4. Be careful when porting from ext/mysql to ext/mysqli. The following
functions return NULL when no more data is available in the result set
(ext/mysql's functions return FALSE).
- mysqli_fetch_row()
- mysqli_fetch_array()
- mysqli_fetch_assoc()
5. PATH_TRANSLATED server variable is no longer set implicitly under
Apache2 SAPI in contrast to the situation in PHP 4, where it is set to the
same value as the SCRIPT_FILENAME server variable when it is not populated
by Apache. This change was made to comply with the CGI specification.
Please refer to bug #23610 for further information.
6. Starting PHP 5.0.0 the T_ML_CONSTANT constant is no longer defined by the
ext/tokenizer extension. If error_reporting is set to E_ALL notices will
be produced. Instead of T_ML_CONSTANT for /* */ the T_COMMENT constant
is used, thus both // and /* */ are resolved as the T_COMMENT constant.
However the PHPDoc style comments /** */ ,which starting PHP 5 are parsed
by PHP, are recongnized as T_DOC_COMMENT.
7. $_SERVER should be populated with argc and argv if variables_order
includes "S". If you have specifically configured your system to not
create $_SERVER, then of course it shouldn't be there. The change was to
always make argc and argv available in the CLI version regardless of the
variables_order setting. As in, the CLI version will now always populate
the global $argc and $argv variables.
8. In some cases classes must be declared before used. It only happens only
if some of the new features of PHP 5 are used. Otherwise the behaviour is
the old.
Example 1 (works with no errors):
$a = new a();
class a {
Example 2 (throws an error):
$a = new a();
interface b{
class a implements b {
Output (example 2) :
Fatal error: Class 'a' not found in /tmp/cl.php on line 2
9. get_class() starting PHP 5 returns the name of the class as it was
declared which may lead to problems in older scripts that rely on
the previous behaviour - the class name is lowercased. Expect the
same behaviour from get_parent_class() when applicable.
Example :
class FooBar {
class ExtFooBar extends FooBar{}
$a = new FooBar();
var_dump(get_class($a), get_parent_class($a));
Output (PHP 4):
string(6) "foobar"
string(9) "extfoobar"
Output (PHP 5):
string(6) "FooBar"
string(9) "ExtFooBar"
Example code that will break :
function someMethod($p) {
if (get_class($p) != 'helpingclass') {
return FALSE;
Possible solution is to search for get_class() and get_parent_class() in
all your scripts and use strtolower().
10. get_class_methods() returns the names of the methods of a class as they
declared. In PHP4 the names are all lowercased.
Example code :
class Foo{
function doFoo(){}
function hasFoo(){}
Output (PHP4):
array(2) {
string(5) "dofoo"
string(6) "hasfoo"
Output (PHP5):
array(2) {
string(5) "doFoo"
string(6) "hasFoo"
11. Assignment $this is impossible. Starting PHP 5.0.0 $this has special
meaning in class methods and is recognized by the PHP parser. The latter
will generate a parse error when assignment to $this is found
Example code :
class Foo {
function assignNew($obj) {
$this = $obj;
$a = new Foo();
$b = new Foo();
echo "I was executed\n";
Output (PHP 4):
I was executed
Output (PHP 5):
PHP Fatal error: Cannot re-assign $this in /tmp/this_ex.php on line 4
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