如何引用同一数组中的数组元素？

Question

我只想在不同的级别从同一个数组引用数组的值。这是否可能，因为在我声明数组之后，我可以正确地引用该元素，但我可以在数组中这样做吗？谢谢!

$literature = [
    'authors'=>[ 
        ['name' => 'hhh', 'adress' => 'hemingway@oldtimers.com','yearOfBirth' => '1869'],
        ['name' => 'yyy', 'adress' => 'saintexupéry@oldtimers.com','yearOfBirth' => '1900'],
        ['name' => 'zzz', 'adress' => 'conandoyle@oldtimers.com','yearOfBirth' => '1859']
    ], 
    'books'=>[
        ['title' => 'ggg', 'author' => $literature ['authors'][0]['name'],  'year' => 1943],
        ['title' => 'uuu', 'author' => $literature ['authors'][0]['name'], 'year' => 1887],
        ['title' => 'ttt!', 'author' => $literature ['authors'][0]['name'], 'year' => 1929],
        ['title' => 'vvv', 'author' => $literature ['authors'][0]['name'], 'year' => 1936],
        ['title' => 'ooo', 'author' => $literature ['authors'][0]['name'], 'year' => 1938]
    ]
];

echo $literature ['authors'][0]['name'];// thats a proper reference, that results in showing the value, but when i print the whole array, that value displays as zero
foreach ($literature as $innerKeylevel1 => $innerDatalevel1) {
    foreach ($innerDatalevel1 as $innerKeylevel2 => $innerDatalevel2) {
        foreach ($innerDatalevel2 as $dataKey => $data) {
            echo  $data . " - ";
        }
        echo "</br>";
    }
}

Answer 1

不能在声明数组的同一部分引用数组--因为表达式是从右到左的(因此它创建数组，在数组中执行所有操作，并将其填充到值中，然后将其赋值给$literature变量)，这意味着在声明和创建数组之前，PHP不知道它是什么--在定义数组之前，您可以不使用它。见PHP:操作符优先。从关于=赋值操作符的手册上看，

Associativity |     Operators                               | Additional Information
--------------+---------------------------------------------+-------------------------
right         | = += -= *= **= /= .= %= &= |= ^= <<= >>=    | assignment

相反，你可以多次声明，首先是作者，然后是书。

$literature = [];
$literature['authors'] = [ 
        ['name' => 'hhh', 'adress' => 'hemingway@oldtimers.com','yearOfBirth' => '1869'],
        ['name' => 'yyy', 'adress' => 'saintexupéry@oldtimers.com','yearOfBirth' => '1900'],
        ['name' => 'zzz', 'adress' => 'conandoyle@oldtimers.com','yearOfBirth' => '1859']
    ];
$literature['books'] = [
        ['title' => 'ggg', 'author' => $literature['authors'][0]['name'],  'year' => 1943],
        ['title' => 'uuu', 'author' => $literature['authors'][0]['name'], 'year' => 1887],
        ['title' => 'ttt!', 'author' => $literature['authors'][0]['name'], 'year' => 1929],
        ['title' => 'vvv', 'author' => $literature['authors'][0]['name'], 'year' => 1936],
        ['title' => 'ooo', 'author' => $literature['authors'][0]['name'], 'year' => 1938]
    ];

print_r($literature);

• https://3v4l.org/JNtua现场演示

Answer 2

我从两个数组开始，然后将它们组合起来。

$authors = [
    ['name' => 'hhh', 'adress' => 'hemingway@oldtimers.com','yearOfBirth' => '1869'],
    ['name' => 'yyy', 'adress' => 'saintexupéry@oldtimers.com','yearOfBirth' => '1900'],
    ['name' => 'zzz', 'adress' => 'conandoyle@oldtimers.com','yearOfBirth' => '1859'],      
];

$books = [
    ['title' => 'ggg', 'author' => $authors ['authors'][0]['name'],  'year' => 1943],
    ['title' => 'uuu', 'author' => $authors ['authors'][0]['name'], 'year' => 1887],
    ['title' => 'ttt!', 'author' => $authors ['authors'][0]['name'], 'year' => 1929],
    ['title' => 'vvv', 'author' => $authors ['authors'][0]['name'], 'year' => 1936],
    ['title' => 'ooo', 'author' => $authors ['authors'][0]['name'], 'year' => 1938]
];

最后：

$literature = [
    'authors'=> $authors,
    'books' => $books,
];