PHP 中的动态数组遍历

Question

我想从一维数组构建层次结构，并且（几乎）可以使用或多或少的硬编码代码来实现。如何使代码动态化？

也许使用 while(isset($array[$key])) { ... } ？ 或者，有额外的功能？像这样： $out = my_extra_traverse_function($array,$key);

function array_traverse($array,$key=NULL) {
    $out = (string) $key;
    $out = $array[$key] . "/" . $out;

    $key = $array[$key];
    $out = $array[$key] ? $array[$key] . "/" . $out : "";
    $key = $array[$key];
    $out = $array[$key] ? $array[$key] . "/" . $out : "";
    $key = $array[$key];
    $out = $array[$key] ? $array[$key] . "/" . $out : "";

    return $out;
}

$a = Array(102=>101, 103=>102, 105=>107, 109=>105, 111=>109, 104=>111);
echo array_traverse($a,104);

输出：107/105/109/111/104

Answer 1

我认为你想要：

function array_traverse($array, $key = null) {
    $out = (string) $key;
    if (isset($array[$key])) {
        $out = array_traverse($array, $array[$key]) . '/' . $out;
    }
    return $out;
}

或者，对于非递归方法：

function array_traverse($array, $key = null) {
    $out = (string) $key;
    while(isset($array[$key])) {
        $out = $array[$key] . '/' . $out;
        $key = $array[$key];
    }
    return $out;
}

Answer 2

是的，我想说 isset() 是正确的方法：

traverse($array, $value) {
    $result = array();
    while (isset($array[$value])) {
        array_unshift($result, $value);
        # or just $result[] = $value if you want to append
        # instead of prepending
        $value = $array[$value];
    }
    return $result;
    # or return implode('/', traverse(array(...))),
    # but I always prefer array return types in such cases:
    # they are much more flexible to the users of the function
}

# BTW: Using implode will avoid having an unnecessary
# leading/trailing delimiter (slash in this case)
echo implode('/', traverse(array(...)));