PHP - variable scope in recursively function - php

Question

First assumption: Assume, we defined a variable (its name is $tmp) in a function(functioin name is 'ExpMenu') for temporary calculating and in end of function we return this variable.
Second assumption: Assume, we call that function recursively for create a navigation menu base on a multidimensional array.
My question is about scope of that variable ($tmp). In every call funtion, will its value overwritten? In other words, by every function call we lose previous value?
For more detail, please review below code:
/// --- { Declaration Block
$content = array(
array(
'level'=>'1',
'order'=>'1',
'text'=>'New Solution WorkFlow',
'is_parent'=>'yes',
'child'=> array(
array(
'level'=>'2',
'order'=>'1',
'text'=>'Define New Solution',
'is_parent'=>'no',
'url'=>'#'
),
array(
'level'=>'2',
'order'=>'2',
'text'=>'View Solutions',
'is_parent'=>'no',
'url'=>'#'
),
array(
'level'=>'2',
'order'=>'3',
'text'=>'View Solutions',
'is_parent'=>'no',
'url'=>'#'
)
)
),
array(
'level'=>'1',
'order'=>'2',
'text'=>'Solution Modify WorkFlow',
'is_parent'=>'yes',
'child'=> array(
array(
'level'=>'2',
'order'=>'1',
'text'=>'Request For Solution Modify',
'is_parent'=>'no',
'url'=>'#'
)
)
),
array(
'level'=>'1',
'order'=>'3',
'text'=>'Solution Close WorkFlow',
'is_parent'=>'yes',
'child'=> array(
array(
'level'=>'2',
'order'=>'1',
'text'=>'Declare For Solution Close',
'is_parent'=>'no',
'url'=>'#'
)
)
)
);
function ExpMenu($item_array ) {
$tmp='';
foreach ($item_array as $item) {
if ($item['is_parent']=='yes') {
$tmp = '<li class="hasChild">' . $item["text"] . '<ul>';
$tmp .= ExpMenu($item['child']);
$tmp .= '</ul></li>';
} else {
$tmp = '<li>';
$tmp .= ''. $item['text'] . '' ;
$tmp .= '</li>';
}
}
return $tmp;
}
/// --- }
$menu='<div><ul>';
$menu .= ExpMenu($content);
$menu.='</ul></div>';
echo $m . '<br />';

Answer 1

It seams by every call function we lose pervious value.
I thank #l0rkaY for her/him solution, But I found another solution that doesn't need add new parameter in my function.
Because $tmp scope is in 'ExpMenu' function and we call recursively function, therefore variable still alive and wasn't terminated.
So, I modify my function a bit:
function ExpMenu($item_array ) {
$tmp='';
foreach ($item_array as $item) {
if ($item['is_parent']=='yes') {
$tmp .= '<li class="hasChild">' . $item["text"] . '<ul>';
$tmp .= ExpMenu($item['child']);
$tmp .= '</ul></li>';
} else {
$tmp .= '<li>';
$tmp .= ''. $item['text'] . '' ;
$tmp .= '</li>';
}
}
return $tmp;
}

Answer 2

I assume your actual problem is, that your function generates only single item with a single child item.
It's because you are overwriting your previous item in your if/else blocks. That's why you only get the last item.
You just need to concatenate them to the existing items.
function ExpMenu($item_array ) {
$tmp='';
foreach ($item_array as $item) {
if ($item['is_parent']=='yes') {
$tmp .= '<li class="hasChild">' . $item["text"] . '<ul>';
$tmp .= ExpMenu($item['child']);
$tmp .= '</ul></li>';
} else {
$tmp .= '<li>';
$tmp .= ''. $item['text'] . '' ;
$tmp .= '</li>';
}
}
return $tmp;
}