多维数组到PHP中的if else语句

hello first sorry for my bad english.

here i have some problem with PHP. how i can create / print (if else) statement from ul and li tag.

I have a multidimentional array like this:

$arr = array(
    array('id' => 1, 'parent' => 0, 'data' => '1.1');
    array('id' => 2, 'parent' => 0, 'data' => '1.2');
    array('id' => 3, 'parent' => 1, 'data' => '1.1.1');
    array('id' => 4, 'parent' => 1, 'data' => '1.1.2');
    array('id' => 5, 'parent' => 2, 'data' => '1.2.1');
    array('id' => 6, 'parent' => 2, 'data' => '1.2.2');
    array('id' => 7, 'parent' => 5, 'data' => '1.2.1.1');
    array('id' => 8, 'parent' => 5, 'data' => '1.2.1.2');
);

Then from the array above i need some code that should echo / print statement like this (IN STRING FORMAT TO SAVE IN A VARIABLE):

$str ='if (1.1) {
    if (1.1.1) {

    } else {

    }
} else {
    if (1.2.1) {
        if (1.2.1.1) {

        }
        else {

        }
    } else {

    }
}';

appreciate for your help... :)

You have to make condition with variable like this:

if ($val == "1.1") {
  //do the child if
}

PHP will not execute this:

if (1.1) {
}

First Step, make new array that's containing child node with key from parent id..

$new_arr = array();
foreach($arr as $a){
    $new_arr[$a['parent']][] = $a;
}

After that, you can access new_array with recursively function..

function rec_child($arr){
    global $new_arr;
    foreach($arr as $a){
        echo "<li>".$a['data']."</li>";
        if(!empty($new_arr[$a['id']])){         
            echo "<ul>";
            rec_child($new_arr[$a['id']]);
            echo "</ul>";
        }
        echo "";
    }
}

So, call rec_child function like this..

echo "<ul>";
rec_child($new_arr[0]);
echo "</ul>";

Hope this help.