php 创建多维数组

$array = array(
    "key1" => array("subkey1" => "value1", "subkey2" => "value2"),
    "key2" => array("subkey3" => "value3", "subkey4" => "value4")
);

$array = [
    "key1" => ["subkey1" => "value1", "subkey2" => "value2"],
    "key2" => ["subkey3" => "value3", "subkey4" => "value4"]
];

<?php
// 创建一个二维数组
$students = [
    ["name" => "Alice", "age" => 20, "grade" => "A"],
    ["name" => "Bob", "age" => 22, "grade" => "B"],
    ["name" => "Charlie", "age" => 21, "grade" => "A"]
];

// 访问二维数组中的元素
echo $students[0]["name"]; // 输出 "Alice"
echo $students[1]["age"];  // 输出 22
?>

if (isset($students[0]["name"])) {
    echo $students[0]["name"];
} else {
    echo "Key does not exist";
}

foreach ($students as $student) {
    foreach ($student as $key => $value) {
        echo "$key: $value\n";
    }
}