只能使用返回值的多维数组的索引

Question

看下面的例子来理解这个想法:

$arr = array
(
    0 => array (
        $this => 3,   // instead 0 => 3,
        'name' => 'three',
    ),
    1 => array (
        $this => 5,   // instead 0 => 5,
        'name' => 'five',
    ),
    2 => array (
        $this => 7,   // instead 0 => 7,
        'name' => 'seven',
    ),
);

对于每个索引都有一个二维数组。而不是调用$arr[0][0]，转而调用$arr[0]。这些都是与期望结果相呼应的想象。

echo $arr[0];           // printing 3
echo $arr[0]['name'];   // printing 'three'
echo $arr[0][0];        // printing 3 (not relevant)

有这样的东西吗?

Answer 1

在PHP 5中，您可以扩展ArrayObject使其成为类似数组的对象。您可以覆盖它的一些行为

class SillyArray extends ArrayObject {
    public function __construct($a)
    {
        foreach($a as $key => $value) {
            if (is_array($value)) {
                $a[$key] = new SillyArray($value);
            }
        }
        parent::__construct($a);
    }
    public function __toString() {
        $result = parent::offsetGet(0);
        if (isset($result)) {
            return (string)$result;
        }
        return "";
    }
}
$a = new SillyArray(
    array(0 => array(
        0 => 3,
        'name' => 'there'
    ))
);
echo $a[0];
echo $a[0][0];
echo $a[0]['name'];

Answer 2

你正在尝试访问多维数组的元素

<?php
         $marks = array( 
            "m" => array
            (
               "physics" => 35,
               "maths" => 30,   
               "chemistry" => 39
            ),
            "q" => array
            (
               "physics" => 30,
               "maths" => 32,
               "chemistry" => 29
            ),
            "z" => array
            (
               "physics" => 31,
               "maths" => 22,
               "chemistry" => 39
            )
         );
         /* Accessing multi-dimensional array values */
         echo "Marks for m in physics : " ;
         echo $marks['m']['physics'] . "<br />"; 
         echo "Marks for q in maths : ";
         echo $marks['q']['maths'] . "<br />"; 
         echo "Marks for z in chemistry : " ;
         echo $marks['z']['chemistry'] . "<br />"; 
      ?>

这将产生

Marks for m in physics : 35
Marks for q in maths : 32
Marks for z in chemistry : 39

https://3v4l.org/bpL4i

现在你的问题是通过调用$arr[0]返回$arr[0][0]的值，就像@icecub说的那样，那么这可以通过

来完成

reset()函数，用于将数组的内部指针移动到第一个元素。链接

实现https://3v4l.org/Ide2L