如果PHP是动态/弱类型语言,为什么我需要PHP中的array()？

Question

我看到很多PHP代码都有值和数组在这里和那里传递,有时候,正好在中间,我看到了$someVar = array();.你什么时候array()在PHP中使用,如果你已经可以传递数组,我认为这应该是PHP的优点之一.

参考PHP手册,例1:

http://php.net/manual/en/functions.arguments.php

<?php
function takes_array($input)
{
    echo "$input[0] + $input[1] = ", $input[0]+$input[1];
}
?>

然后从另一个网站的其他地方:

/**
 * Model for accessing schedule table
 *
 * @author Chris Hartjes
 */

class Schedule extends AppModel
{
    var $name = 'Schedule';
    var $useTable = 'sched2007';
    var $useDbConfig = 'stats';

    function get($week) {
        $scheduledGames = array();
        $team = array("a01" => "BUF", "a02" => "COU", "a03" => "HAG", "a04" => "TRI",
                    "a05" => "BOW", "a06" => "MCM", "a07" => "PHI", "a08" => "WMS",
                    "a09" => "LAW", "a10" => "PAD", "a11" => "POR", "a12" => "STL",
                    "n01" => "CSP", "n02" => "COL", "n03" => "MIN", "n04" => "SDQ",
                    "n05" => "BUZ", "n06" => "CAJ", "n07" => "DTR", "n08" => "SCS",
                    "n09" => "CRE", "n10" => "MAD", "n11" => "SEA", "n12" => "SPO");
        $results = $this->findAll("home LIKE 'a%' AND week = " . (int)$week);
        $data = array();

        foreach ($results as $result) {
            $home = $team[$result['Schedule']['home']];
            $away = $team[$result['Schedule']['away']];
            $data[$home] = array('home' => $home, 'away' => $away);
        }

        asort($data);

        foreach ($data as $home => $matchup) {
            $scheduledGames[$home] = $matchup;
        }

        $results = $this->findAll("home LIKE 'n%' AND week = " . (int)$week);
        $data = array();

        foreach ($results as $result) {
            $home = $team[$result['Schedule']['home']];
            $away = $team[$result['Schedule']['away']];
            $data[$home] = array('home' => $home, 'away' => $away);
        }

        asort($data);

        foreach ($data as $home => $matchup) {
            $scheduledGames[$home] = $matchup;
        }

        return $scheduledGames;
    }
}

在这里$scheduledGames你有array(),然后$team只是动态显示它的数组,然后$data再次有array().

然而,正如评论中所指出的那样,冒着成为笨蛋的风险,我相信我会把它与隐式数组混淆,所以当它的一个键被赋予某些东西时,是否在PHP中隐式创建数组？

Answer 1

如果你可以传递数组,那意味着你需要一些方法来创建数组,对吗？就是这样array(),它是创建数组的语言构造.

这种代码只是最佳实践:

$foo = array();

foreach ($bar as $baz) {
    $foo[] = $baz;
}

return $foo;

如果$bar是空的怎么办？然后循环不会运行.如果$foo在循环之前没有初始化为数组,则循环后它将不存在.在这种情况下return $foo会抛出一个错误,因为你试图返回一些不存在的东西.因此,您始终初始化您要处理的变量.这就是你在几乎所有语言中所做的事情.