遍历"父级"中的PHP数组可以使用循环结构和递归方法。下面是一些示例代码：

1. 使用foreach循环遍历父级数组：

$parentArray = [
    "key1" => "value1",
    "key2" => "value2",
    "key3" => [
        "subkey1" => "subvalue1",
        "subkey2" => "subvalue2"
    ],
    "key4" => "value4"
];

foreach ($parentArray as $key => $value) {
    if (is_array($value)) {
        // 对于数组类型的值，可以使用递归方法进行遍历
        foreach ($value as $subkey => $subvalue) {
            echo "[$key][$subkey] = $subvalue" . PHP_EOL;
        }
    } else {
        echo "[$key] = $value" . PHP_EOL;
    }
}

输出结果：

[key1] = value1
[key2] = value2
[key3][subkey1] = subvalue1
[key3][subkey2] = subvalue2
[key4] = value4

2. 使用递归方法遍历父级数组：

function traverseArray($array, $prefix = "") {
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            // 递归调用遍历子数组
            traverseArray($value, $prefix . "[$key]");
        } else {
            echo "$prefix[$key] = $value" . PHP_EOL;
        }
    }
}

$parentArray = [
    "key1" => "value1",
    "key2" => "value2",
    "key3" => [
        "subkey1" => "subvalue1",
        "subkey2" => "subvalue2"
    ],
    "key4" => "value4"
];

traverseArray($parentArray);

输出结果：

[key1] = value1
[key2] = value2
[key3][subkey1] = subvalue1
[key3][subkey2] = subvalue2
[key4] = value4

这些示例代码可以帮助您遍历"父级"中的PHP数组，无论数组的层级有多深。根据您的需求选择合适的方法进行遍历。