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The PHP manual text and comments are covered by the Creative Commons Attribution 3.0 License © the PHP Documentation Group - Impressum - mail("TO:Reinhard Neidl",...)
Wenn innerhalb einer Funktion aufgerufen, beendet return() augenblicklich die Ausführung der Funktion und übergibt den Parameter als Rückgabewert der Funktion. return() beendet ebenfalls die Ausführung von Code innerhalb von eval() oder einer Datei.
Wenn im globalen Raum aufgerufen, endet die Ausführung des Skripts. Wenn das aktuelle Skript mit include() oder require() eingebunden ist, endet nur die Ausführung der eingebundenen Datei und der Wert, der an return() übergeben wurde, wird zum Rückgabewert des Aufrufs von include()/require(). Wenn return() im Hauptskript aufgerufen wird, endet das gesamte Skript. Wenn das aktuelle Skript durch die Konfigurationsdirektiven auto_prepend_file oder auto_append_file aufgerufen wurde, wird die Ausführung dieses Skripts beendet.
Für mehr Informationen, siehe die Dokumentation zu Rückgabewerten.
Hinweis: Weil return() ein Sprachkonstrukt und keine Funktion ist, sind die Klammern um das Argument optional. Es ist üblich, sie auszulassen, und dies wird ausdrücklich empfohlen, weil PHP in diesem Fall weniger zu tun hat.
Hinweis: Wenn kein Parameter übergeben wird, dürfen die Klammern nicht gesetzt werden und NULL wird zurückgegeben. Der Aufruf von return() mit Klammern aber ohne Parameter verursacht einen Parse Error.
Hinweis: Das Zurückgeben von Referenzen funktioniert nicht, wenn Klammern um den Parameter verwendet werden. Bei return ($a); wird nicht die Variable $a sondern das Ergebnis des Ausdrucks ($a) zurückgegeben (was selbstverständlich der Wert von $a ist).
@Radu
http://www.php.net/manual/en/language.operators.assignment.php
"The value of an assignment expression is the value assigned."
Note "the value assigned", not "the value assigned to".
The value assigned in the expression $a['e'] = 'sometxt' is 'sometxt', and that's what you're returning in function a().
When returning an array, you should declare the array before the return, else the result is not as you expect;
Watch this example:
<?php
function a(){
return $a['e'] = 'sometxt';
}
function b(){
$a['e'] = 'sometxt';
return $a;
}
function c(){
if(is_array(a())){
echo 'a is array';
}else{
echo 'a is NOT an array';
}
if(is_array(b())){
echo 'b is array';
}else{
echo 'b is NOT an array';
}
}
?>
This will print:
a is NOT an array
b is array
NB: using return to exit a command-line script will not use the return value as the script's return value. To do that, you need to use, eg, exit(1);
A side note when you return a conditional value the variable type will inherit its type of Boolean
For example
<?php
function foo($SQL){
$conTemp = new mysqli("locahost", "root", "", "");
$conTemp->select_db("MyDB");
return $conTemp->query($SQL) or die("Query Failed!");
}
$result = foo("SELECT UserName FROM Users LIMIT 1");
echo gettype($result); //returns Boolean instead of object or die
?>
Instead be explicit with your function like so
<?php
function foo($SQL){
$conTemp = new mysqli("locahost", "root", "", "");
$conTemp->select_db("MyDB");
if(!$result = $conTemp->query($SQL)){
return die("Query Failed");
}
return $result;
}
$result = foo("SELECT UserName FROM Users LIMIT 1");
echo gettype($result); //Now will return Object or die
?>
As obvious as it may seem, it might still be useful to point out that return called without any value returns null.
<?php
function test() {
return;
}
print gettype(test()) . "\n";
print (test()?'true':'false') . "\n";
print (!test()?'true':'false') . "\n";
print (test() === false?'true':'false') . "\n";
?>
This returns:
NULL
false
true
false
Response to stoic's message below...
I believe the way you've explained this for people may be a bit confusing, and your verbiage is incorrect. Your script below is technically calling return from a global scope, but as it says right after that in the description above... "If the current script file was include()ed or require()ed, then control is passed back to the calling file". You are in a included file. Just making sure that is clear.
Now, the way php works is before it executes actual code it does what you call "processing" is really just a syntax check. It does this every time per-file that is included before executing that file. This is a GOOD feature, as it makes sure not to run any part of non-functional code. What your example might have also said... is that in doing this syntax check it does not execute code, merely runs through your file (or include) checking for syntax errors before execution. To show that, you should put the echo "b"; and echo "a"; at the start of each file. This will show that "b" is echoed once, and then "a" is echoed only once, because the first time it syntax checked a.php, it was ok. But the second time the syntax check failed and thus it was not executed again and terminated execution of the application due to a syntax error.
Just something to help clarify what you have stated in your comments.
Just to clear things up, if using return on a global scope it will end EXECUTION but NOT PROCESSING.
for example:
file a.php
<?php
if(defined("A")) return;
define("A", true);
echo "Hello";
?>
file b.php
<?php
include("a.php");
include("a.php");
?>
will output "Hello" only once.
but if file a.php is
<?php
if(defined("A")) return;
define("A", true);
function foo(){
}
?>
running file b.php will produce error:
Fatal Error: Cannot redeclare foo()...
direct true 0.59850406646729
direct false 0.62642693519592
indirect true 0.75077891349792
indirect false 0.73496103286743
It is generally more true, because indirect method implies creating additional variable and assigning a value to it.
But, you know, "results may vary".
I was wondering what was quicker:
- return a boolean as soon I know it's value ('direct') or
- save the boolean in a variable and return it at the function's end.
<?php
$times = 50000;
function return_direct ($boolean)
{
if ($boolean == true)
{
return true;
}
return false;
}
function return_indirect ($boolean)
{
$return = false;
if ($boolean == true)
{
$return = true;
}
return $return;
}
/* Direct, return true */
$time_start = microtime(true);
for ($i = 1; $i <= $times; $i++)
{
return_direct(true);
}
$time_end = microtime(true);
$time_direct_true = $time_end - $time_start;
/* Direct, return false */
$time_start = microtime(true);
for ($i = 1; $i <= $times; $i++)
{
return_direct(false);
}
$time_end = microtime(true);
$time_direct_false = $time_end - $time_start;
/* Indirect, return true */
$time_start = microtime(true);
for ($i = 1; $i <= $times; $i++)
{
return_indirect(true);
}
$time_end = microtime(true);
$time_indirect_true = $time_end - $time_start;
/* Direct, return false */
$time_start = microtime(true);
for ($i = 1; $i <= $times; $i++)
{
return_indirect(false);
}
$time_end = microtime(true);
$time_indirect_false = $time_end - $time_start;
echo "<pre>";
echo "direct true\t" . $time_direct_true;
echo "\ndirect false\t" . $time_direct_false;
echo "\nindirect true\t" . $time_indirect_true;
echo "\nindirect false\t" . $time_indirect_false;
echo "<pre>";
?>
Representative results:
direct true 0.163973093033
direct false 0.1270840168
indirect true 0.0733940601349
indirect false 0.0742440223694
Conclusion: saving the result in a variable appears to be faster. (Please note that my test functions are very simple, maybe it's slower on longer functions)
regardez this code:
print pewt( "hello!" );
function pewt( $arg )
{
include( "some_code.inc" );
}
some_code.inc:
return strtoupper( $arg );
.. after much hair pulling, discovered why nothing was being returned by the "some_code.inc" code in the function .. the return simply returns the result TO the function (giving the include function a value), not to the CALLING (print pewt). This works:
print pewt( "hello!" );
function pewt( $arg )
{
return include( "some_code.inc" );
}
So, RETURN works relative to block it is executed within.
for those of you who think that using return in a script is the same as using exit note that: using return just exits the execution of the current script, exit the whole execution.
look at that example:
a.php
<?php
include("b.php");
echo "a";
?>
b.php
<?php
echo "b";
return;
?>
(executing a.php:) will echo "ba".
whereas (b.php modified):
a.php
<?php
include("b.php");
echo "a";
?>
b.php
<?php
echo "b";
exit;
?>
(executing a.php:) will echo "b".
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