在PHP 5.5中还有一个新概念:生成器，你可以从一个函数中产生多个值:

function hasMultipleValues() {
    yield "value1";
    yield "value2";
}

$values = hasMultipleValues();
foreach ($values as $val) {
    // $val will first be "value1" then "value2"
}

最佳实践是将返回的变量放入数组，然后使用list()将数组值赋给变量。

<?php

function add_subt($val1, $val2) {
    $add = $val1 + $val2;
    $subt = $val1 - $val2;

    return array($add, $subt);
}

list($add_result, $subt_result) = add_subt(20, 7);
echo "Add: " . $add_result . '<br />';
echo "Subtract: " . $subt_result . '<br />';

?>

这是最简单的方法:

public function selectAllUsersByRole($userRole, $selector) {

    $this->userRole = $userLevel;
    $this->selector = $selector;

    $sql = "SELECT * FROM users WHERE role <= ? AND del_stat = 0";
    $stm = $this->connect()->prepare($sql); // Connect function in Dbh connect to database file
    $stm->execute([$this->userRole]); // This is PHP 7. Use array($this->userRole) for PHP 5

    $usersIdArray = array();
    $usersFNameArray = array();
    $usersLNameArray = array();

    if($stm->rowCount()) {
        while($row = $stm->fetch()) {

            array_push($usersIdArray,    $row['id']);
            array_push($usersFNameArray, $row['f_name']);
            array_push($usersLNameArray, $row['l_name']);

            // You can return only $row['id'] or f_name or ...
            // I used the array because it's most used.
        }
    }
    if($this->selector == 1) {
        return $usersIdArray;
    }elseif($this->selector == 2) {
        return $usersFNameArray;
    }elseif($this->selector == 3) {
        return $usersLNameArray;
    }

}

我们如何调用这个函数呢?

$idData = $selectAllUsers->selectAllUsersByLevel($userRole, 0);
print_r($idData);
$idFName = $selectAllUsers->selectAllUsersByLevel($userRole, 1);
print_r($idFname);

就是这样。非常容易。

从PHP 7.1开始，我们对列表进行了适当的解构。 因此你可以这样做:

$test = [1, 2, 3, 4];
[$a, $b, $c, $d] = $test;
echo($a);
> 1
echo($d);
> 4

在函数中是这样的:

function multiple_return() {
    return ['this', 'is', 'a', 'test'];
}

[$first, $second, $third, $fourth] = multiple_return();
echo($first);
> this
echo($fourth);
> test

解构是一个非常强大的工具。它也能够解构key=>值对:

["a" => $a, "b" => $b, "c" => $c] = ["a" => 1, "b" => 2, "c" => 3];

看看PHP 7.1的新特性页面:

新功能

没有办法返回两个变量。虽然，你可以传播一个数组并返回它;创建一个条件返回一个动态变量，等等。

例如，这个函数将返回$var2

function wtf($blahblah = true) {
    $var1 = "ONe";
    $var2 = "tWo";

    if($blahblah === true) {
      return $var2;
    }
    return $var1;
}

在应用程序:

echo wtf();
//would echo: tWo
echo wtf("not true, this is false");
//would echo: ONe

如果你两个都想要，你可以稍微修改一下函数

function wtf($blahblah = true) {
    $var1 = "ONe";
    $var2 = "tWo";

    if($blahblah === true) {
      return $var2;
    }

    if($blahblah == "both") {
      return array($var1, $var2);
    }

    return $var1;
}

echo wtf("both")[0]
//would echo: ONe
echo wtf("both")[1]
//would echo: tWo

list($first, $second) = wtf("both")
// value of $first would be $var1, value of $second would be $var2

允许多次返回的语言通常只是将多个值转换为一个数据结构。

例如，在Python中，您可以返回多个值。但是，它们实际上只是作为一个元组返回。

你可以在PHP中返回多个值只需创建一个简单数组并返回。