php数组 元素提取

<?php
$fruits = array("Apple", "Banana", "Cherry");

// 提取第一个元素
echo $fruits[0]; // 输出: Apple
?>

<?php
$person = array(
    "name" => "John",
    "age" => 30,
    "city" => "New York"
);

// 提取name键对应的值
echo $person["name"]; // 输出: John
?>

<?php
$person = array(
    "name" => "John",
    "age" => 30
);

if (isset($person["city"])) {
    echo $person["city"];
} else {
    echo "City is not set";
}
?>

<?php
$fruits = array("Apple", "Banana");

if ($index < count($fruits)) {
    echo $fruits[$index];
} else {
    echo "Index out of bounds";
}
?>

<?php
$fruits = array("Apple", "Banana");

// 错误示例
echo $fruits["Apple"]; // 会导致警告

// 正确示例
echo $fruits[0]; // 输出: Apple
?>