how to return static variable PHP

Question

function build_path($cid)
{
    static $fr=array();
    $DB = new MySQLTable;
    $DB->TblName = 'shop_categories';
    $where['cat_id']['='] = $cid;
    $res = $DB->Select('cat_id,cat_name,cat_parent', $where);
    if($res !== false)
    {
        $pid = mysql_fetch_array($res);
        if($pid['cat_parent'] !== "0")
        {
           $fr[] = $pid['cat_id'];
           build_path($pid['cat_parent']);
        } else {
            $fr[] = $cid;
            $fr = array_reverse($fr);
            print_r($fr);
            return $fr;
        }
    }
}

print_r(build_path(100));

Why is working print_r in function, but second print_r returns NULL?

is it for sure going into the last else code block and executing return $fr? — Joshua Pinter, Jun 14 '10 at 22:52
ALL IS WORK. I was just moved return instruction to the end of function. THNKS 2 ALL!!! — GOsha, Jun 15 '10 at 00:22

score 4 · Accepted Answer · answered Jun 14 '10 at 22:59

4

Normally, for a recursive function to work, you need to return something when calling itself.

Try this in your first nested if block:

return build_path($pid['cat_parent']);

answered Jun 14 '10 at 22:59

Mike B

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score 2 · Answer 2 · edited May 23 '17 at 12:07

2

FYI, You wouldn't need to write a recursive function or execute N queries for N levels of hierarchy if you used one of the various methods for storing hierarchical data in a database.

edited May 23 '17 at 12:07

Community

1
1

answered Jun 14 '10 at 23:03

Bill Karwin

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score 0 · Answer 3 · answered Jun 14 '10 at 23:00

0

Recursive functions must not use static to pass the data through invokes - use the arguments instead.

And why do you need this line:

if($res !== false)

??

answered Jun 14 '10 at 23:00

zerkms

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this class returns resource id if query is ok, and false if i have mysql error – GOsha Jun 15 '10 at 00:21
@GOsha: if you write proper queries - you would never get mysql query error – zerkms Jun 15 '10 at 02:00
If server is down it is better to throw an exception. – zerkms Jun 15 '10 at 11:04

score 0 · Answer 4 · answered Jun 14 '10 at 23:11

0

Instead of build_path($pid['cat_parent']); in line 14 use return build_path($pid['cat_parent']);.

answered Jun 14 '10 at 23:11

powtac

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how to return static variable PHP

4 Answers4