html as php variable not rendered properly - php

Question

Having the following method
public function printDropdownTree($tree, $r = 0, $p = null) {
foreach ($tree as $i => $t) {
$dash = ($t['parent'] == 0) ? '' : str_repeat('-', $r) . ' ';
printf("\t<option value='%d'>%s%s</option>\n", $t['id'], $dash, $t['name']);
if ($t['parent'] == $p) {
// reset $r
$r = 0;
}
if (isset($t['_children'])) {
$this->printDropdownTree($t['_children'], ++$r, $t['parent']);
}
}
}
which prints out nested select options and which works fine. But I would like to return the result as variable and I was trying to achieve this like
public function printDropdownTree($tree, $r = 0, $p = null) {
$html = "";
foreach ($tree as $i => $t) {
$dash = ($t['parent'] == 0) ? '' : str_repeat('-', $r) . ' ';
$html .= '<option value="'.$t['id'].'">'.$dash.''.$t['name'].'</option>';
if ($t['parent'] == $p) {
// reset $r
$r = 0;
}
if (isset($t['_children'])) {
$this->printDropdownTree($t['_children'], ++$r, $t['parent']);
}
}
return $html;
}
but the $dash won't get rendered

Answer 1

The simple solution: You have to fetch the result of the recursive calls of the function!
public function printDropdownTree($tree, $r = 0, $p = null) {
$html = "";
foreach ($tree as $i => $t) {
$dash = ($t['parent'] == 0) ? '' : str_repeat('-', $r) . ' ';
$html .= '<option value="'.$t['id'].'">'.$dash.''.$t['name'].'</option>';
if ($t['parent'] == $p) {
// reset $r
$r = 0;
}
if (isset($t['_children'])) {
$html .= $this->printDropdownTree($t['_children'], ++$r, $t['parent']);
}
}
return $html;
}