Returning values

    Values are returned by using the optional return statement. Any type may be returned, including arrays and objects. This causes the function to end its execution immediately and pass control back to the line from which it was called. See return for more information.

    Зауваження:

    If the return is omitted the value null will be returned.

    Use of return

    Приклад #1 Use of return

    <?php
    function square($num)
    {
    return     $num * $num;
    }
    echo     square(4); // outputs '16'.
    ?>

    A function can not return multiple values, but similar results can be obtained by returning an array.

    Приклад #2 Returning an array to get multiple values

    <?php
    function small_numbers()
    {
    return [    0, 1, 2];
    }
    // Array destructuring will collect each member of the array individually
    [$zero, $one, $two] = small_numbers();

    // Prior to 7.1.0, the only equivalent alternative is using list() construct
    list($zero, $one, $two) = small_numbers();

    ?>

    To return a reference from a function, use the reference operator & in both the function declaration and when assigning the returned value to a variable:

    Приклад #3 Returning a reference from a function

    <?php
    function &returns_reference()
    {
    return     $someref;
    }

    $newref =& returns_reference();
    ?>

    For more information on references, please check out References Explained.

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    User Contributed Notes 4 notes

    up
    24
    rstaveley at seseit dot com
    14 years ago
    Developers with a C background may expect pass by reference semantics for arrays. It may be surprising that pass by value is used for arrays just like scalars. Objects are implicitly passed by reference.

    <?php

    # (1) Objects are always passed by reference and returned by reference

    class Obj {
    public     $x;
    }

    function     obj_inc_x($obj) {
    $obj->x++;
    return     $obj;
    }

    $obj = new Obj();
    $obj->x = 1;

    $obj2 = obj_inc_x($obj);
    obj_inc_x($obj2);

    print     $obj->x . ', ' . $obj2->x . "\n";

    # (2) Scalars are not passed by reference or returned as such

    function scalar_inc_x($x) {
    $x++;
    return     $x;
    }

    $x = 1;

    $x2 = scalar_inc_x($x);
    scalar_inc_x($x2);

    print     $x . ', ' . $x2 . "\n";

    # (3) You have to force pass by reference and return by reference on scalars

    function &scalar_ref_inc_x(&$x) {
    $x++;
    return     $x;
    }

    $x = 1;

    $x2 =& scalar_ref_inc_x($x); # Need reference here as well as the function sig
    scalar_ref_inc_x($x2);

    print     $x . ', ' . $x2 . "\n";

    # (4) Arrays use pass by value sematics just like scalars

    function array_inc_x($array) {
    $array{'x'}++;
    return     $array;
    }

    $array = array();
    $array['x'] = 1;

    $array2 = array_inc_x($array);
    array_inc_x($array2);

    print     $array['x'] . ', ' . $array2['x'] . "\n";

    # (5) You have to force pass by reference and return by reference on arrays

    function &array_ref_inc_x(&$array) {
    $array{'x'}++;
    return     $array;
    }

    $array = array();
    $array['x'] = 1;

    $array2 =& array_ref_inc_x($array); # Need reference here as well as the function sig
    array_ref_inc_x($array2);

    print     $array['x'] . ', ' . $array2['x'] . "\n";
    up
    23
    ryan dot jentzsch at gmail dot com
    7 years ago
    PHP 7.1 allows for void and null return types by preceding the type declaration with a ? -- (e.g. function canReturnNullorString(): ?string)

    However resource is not allowed as a return type:

    <?php
    function fileOpen(string $fileName, string $mode): resource
    {
    $handle = fopen($fileName, $mode);
    if (    $handle !== false)
    {
    return     $handle;
    }
    }

    $resourceHandle = fileOpen("myfile.txt", "r");
    ?>

    Errors with:
    Fatal error: Uncaught TypeError: Return value of fileOpen() must be an instance of resource, resource returned.
    up
    13
    bgalloway at citycarshare dot org
    16 years ago
    Be careful about using "do this thing or die()" logic in your return lines. It doesn't work as you'd expect:

    <?php
    function myfunc1() {
    return(    'thingy' or die('otherthingy'));
    }
    function     myfunc2() {
    return     'thingy' or die('otherthingy');
    }
    function     myfunc3() {
    return(    'thingy') or die('otherthingy');
    }
    function     myfunc4() {
    return     'thingy' or 'otherthingy';
    }
    function     myfunc5() {
    $x = 'thingy' or 'otherthingy'; return $x;
    }
    echo     myfunc1(). "\n". myfunc2(). "\n". myfunc3(). "\n". myfunc4(). "\n". myfunc5(). "\n";
    ?>

    Only myfunc5() returns 'thingy' - the rest return 1.
    up
    7
    nick at itomic.com
    21 years ago
    Functions which return references, may return a NULL value. This is inconsistent with the fact that function parameters passed by reference can't be passed as NULL (or in fact anything which isnt a variable).

    i.e.

    <?php

    function &testRet()
    {
    return     NULL;
    }

    if (    testRet() === NULL)
    {
    echo     "NULL";
    }
    ?>

    parses fine and echoes NULL
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