PHP多维数组通过字符串路径进行深度查找

<?php

$arr = [
    0 => [
        0 => "1-1",
        1 => "1-2",
        2 => "1-3",
        3 => [
            0 => "1-4-1",
            1 => "1-4-2",
            2 => "1-4-3"
        ]
    ],
    1 => [
        0 => "2-1",
        1 => "2-2",
        2 => "2-3"
    ],
    2 => [
        0 => "3-1",
        1 => "3-2",
        2 => "3-3",
        3 => [
            0 => "3-4-1",
            1 => "3-4-2"
        ]
    ],
];

// 示例输入：查找 $arr[2][3][0]
$input = "230"; 

// 初始化结果变量，从原始数组开始
$result = $arr;

// 遍历输入字符串的每个字符作为键
for ($i = 0; $i < strlen($input); $i++) {
    // 检查当前 $result 是否仍然是一个数组
    if (is_array($result)) {
        // 如果是数组，则尝试使用当前字符作为键访问下一层
        // 注意：PHP会将数字字符串键自动转换为整数键
        if (isset($result[$input[$i]])) {
            $result = $result[$input[$i]];
        } else {
            // 键不存在，路径中断
            $result = 'Error: Path segment "' . $input[$i] . '" does not exist.';
            break;
        }
    } else {
        // 当前 $result 已不是数组，无法继续遍历
        $result = 'Error: Cannot traverse path beyond a non-array value.';
        break;
    }
}

echo $result; // 输出: 3-4-1

echo "\n";

// 示例2：查找不存在的路径
$input_invalid = "021"; // 0 -> 2 (值 "1-3") -> 1 (无法继续)
$result_invalid = $arr;
for ($i = 0; $i < strlen($input_invalid); $i++) {
    if (is_array($result_invalid)) {
        if (isset($result_invalid[$input_invalid[$i]])) {
            $result_invalid = $result_invalid[$input_invalid[$i]];
        } else {
            $result_invalid = 'Error: Path segment "' . $input_invalid[$i] . '" does not exist.';
            break;
        }
    } else {
        $result_invalid = 'Error: Cannot traverse path beyond a non-array value.';
        break;
    }
}
echo $result_invalid; // 输出: Error: Cannot traverse path beyond a non-array value.

?>

<?php

function searchByPathString(array $array, string $pathString)
{
    $current = $array;

    for ($i = 0; $i < strlen($pathString); $i++) {
        $key = $pathString[$i]; // 获取当前路径段的键

        // 检查当前是否为数组，且键是否存在
        if (is_array($current) && isset($current[$key])) {
            $current = $current[$key]; // 深入到下一层
        } else {
            // 路径中断：当前不是数组，或者键不存在
            return 'Error: Path segment "' . $key . '" is invalid or does not exist at this level.';
        }
    }
    return $current; // 返回最终找到的值或错误信息
}

$arr = [
    0 => [
        0 => "1-1",
        1 => "1-2",
        2 => "1-3",
        3 => [
            0 => "1-4-1",
            1 => "1-4-2",
            2 => "1-4-3"
        ]
    ],
    1 => [
        0 => "2-1",
        1 => "2-2",
        2 => "2-3"
    ],
    2 => [
        0 => "3-1",
        1 => "3-2",
        2 => "3-3",
        3 => [
            0 => "3-4-1",
            1 => "3-4-2"
        ]
    ],
];

// 成功示例
echo "Path '230' result: " . searchByPathString($arr, "230") . "\n"; // 输出: 3-4-1

// 路径中断示例：0 -> 2 (值为 "1-3")，尝试继续访问 "1"
echo "Path '021' result: " . searchByPathString($arr, "021") . "\n"; 
// 输出: Error: Path segment "1" is invalid or does not exist at this level.

// 键不存在示例：2 -> 3 -> 9 (键9不存在)
echo "Path '239' result: " . searchByPathString($arr, "239") . "\n"; 
// 输出: Error: Path segment "9" is invalid or does not exist at this level.

// 根键不存在示例
echo "Path '9' result: " . searchByPathString($arr, "9") . "\n"; 
// 输出: Error: Path segment "9" is invalid or does not exist at this level.

?>