Recursive function in PHP
recursive function is a function that calls itself repeatedly for a specified condition.
Here is an example function which calls itself to perform a tree structure for a category table
Here is the category table:
| category_id | parent_id | category_name |
| 1 | 0 | CMS |
| 2 | 0 | Blogs |
| 3 | 0 | Forums |
| 4 | 0 | E-Commerce |
| 5 | 1 | Joomla |
| 6 | 1 | Mambo |
| 7 | 6 | Templates |
| 8 | 6 | Mods/Components |
| 9 | 4 | OSCommerce |
| 10 | 2 | Wordpress |
| 11 | 10 | Themes |
| 12 | 10 | Plugins |
<?php
echo '<select name="category">
<option value="0">Root</option>';
$allcats = getTree();
foreach($allcats as $key=>$value)
{
echo "<option value='$key'>$value</option>";
}
echo '</select>';
foreach($allcats as $key=>$value)
{
echo "$value";
}
echo '
';
function getTree($id=0)
{
static $cates = array();
static $times = 0;
$times++;
$result = mysql_query("SELECT category_id,category_name FROM category_table WHERE parent_id=$id ORDER BY category_name");
while($row = mysql_fetch_assoc($result))
{
$cates[$row['category_id']] = str_repeat("| ",$times-1)."|___".$row['category_name'];
getTree($row['category_id']);
}
$times---;
return $cates;
}
?>
The out put of this program would be the following select box: