declare
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".
return
(PHP 4, PHP 5)
Si se llama desde una función, la sentencia return inmediatamente termina la ejecución de la función actual, y devuelve su argumento como el valor de la llamada a la función. return también pondrá fin a la ejecución de una sentencia eval() o a un archivo de script.
Si se llama desde el ámbito global, entonces la ejecución del script actual se termina. Si el archivo script actual fue incluido o requerido con include o require, entonces el control es pasado de regreso al archivo que hizo el llamado. Además, si el archivo script actual fue incluido con include, entonces el valor dado a return será retornado como el valor de la llamada include. Si return es llamado desde dentro del fichero del script principal, entonces termina la ejecución del script. Si el archivo script actual fue nombrado por las opciones de configuración auto_prepend_file o auto_append_file en php.ini, entonces se termina la ejecución de ese archivo script.
Para más información, ver Retornando valores.
Nota: Cabe señalar que dado que return es un constructor del lenguaje y no una función, los paréntesis que rodean su argumentos no son necesarios. Es común no utilizarlos, y en realidad se debería hacer así a fin de que PHP tenga menos trabajo que hacer en este caso.
Nota: Si no se suministra un parámetro, entonces el paréntesis debe omitirse y
NULLserá retornado. Llamadas a return con paréntesis pero sin argumentos resultarán en un error del intérprete.
Nota: Nunca se deben usar paréntesis al rededor de la variable de retorno cuando se retorna por referencia, ya que esto no funcionará. Sólo se pueden retornar variables por referencia, no el resultado de una sentencia. Si se utiliza return ($a); entonces no se está retornando una variable, sino el resultado de la expresión ($a) (el cual es, por supuesto, el valor de $a).
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User Contributed Notes
return - [11 notes]
Denis.Gorbachev ¶
5 years ago
pgl at yoyo dot org ¶
3 years ago
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);
MrLavender ¶
3 years ago
@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().
andrew at neonsurge dot com ¶
4 years ago
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.
list at regularoddity dot com ¶
4 years ago
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
mr dot xanadu at gmail dot com ¶
5 years ago
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)
Radu ¶
3 years ago
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 $a;
}
function c(){
if(is_array(a())){
echo 'a is array';
}else{
echo 'a is NOT an array';
}
if(is_array(b())){
echo 'b is array';
}else{
echo 'b is NOT an array';
}
}
?>
This will print:
a is NOT an array
b is array
warhog at warhog dot net ¶
7 years ago
for those of you who think that using return in a script is the same as using exit note that: using return just exits the execution of the current script, exit the whole execution.
look at that example:
a.php
<?php
include("b.php");
echo "a";
?>
b.php
<?php
echo "b";
return;
?>
(executing a.php:) will echo "ba".
whereas (b.php modified):
a.php
<?php
include("b.php");
echo "a";
?>
b.php
<?php
echo "b";
exit;
?>
(executing a.php:) will echo "b".
fyrye ¶
3 years ago
A side note when you return a conditional value the variable type will inherit its type of Boolean
For example
<?php
function foo($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
?>
stoic ¶
4 years ago
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()...
Spacecat ¶
5 years ago
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.