动态PHP中的数组遍历遍历

Question

我想从一维数组构建一个层次结构，并且可以（几乎）用一个或多或少的硬编码代码来实现。我怎样才能使代码动态？

也许与while(isset($array[$key])) { ... }？ 或者，还有一个额外的功能？就像这样：$out = my_extra_traverse_function($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

：

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，我会说isset()是要走的路：你想我想

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(...)));