Replacing goto with a function, why doesn't this work?

Question

I've been trying to change some code for a validation script so that it doesn't include goto, as I want to run my scripts on a webhost, and unfortunately most of them don't really have 5.3 or later.

The code is meant to use a value generated by rand for a unique validation number. If it finds it already in the DB, it will append 1 on to the number as many times as it needs to until it finds a usable number. Pretty straightforward. I know it's terrible practice for a MySQL query, but it's really just a simple script for practice.

The code is as follows:

function gen_val($val)
{
    $query = mysql_query("SELECT val_id FROM users_tmp WHERE val_id=$val");
    $row = mysql_fetch_array($query);
    if ($row[0]==$val) {
        gen_val($val+1);
    } else {
        return $val;
    }
}

$val_x=gen_val(rand());

This returns a value '0' if the value already existed in the DB. Function works fine if there's no similar value already, so I think there's a problem with the function recursing. I don't think I really know how to use it properly, so please go ahead and educate me.

Cheers.

Asher

Just FYI as your database grows this particular function is going to get slower and slower. MySQL has unique id functionality built in, this is unnecessary. — Chris Eberle
– Chris Eberle, Commented May 8, 2011 at 6:09

Ignacio Vazquez-Abrams · Accepted Answer · 2011-05-08 05:42:34Z

2

You forgot to return the result of your recursion.

return gen_val($val+1);

answered May 8, 2011 at 5:42

Ignacio Vazquez-Abrams

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4 Comments

Cyber Slueth Omega Over a year ago

It does return the value on only the last iteration of the recursion that meets the if condition, but every subsequent completion, the return value is not returned including the first iteration of calling gen_val.

Ignacio Vazquez-Abrams Over a year ago

Because recursion doesn't always involve returning something.

Ignacio Vazquez-Abrams Over a year ago

It returns $val because you wrote return $val. It does not return $val on its own.

Ignacio Vazquez-Abrams Over a year ago

Because those are two independent function calls.

Nick ODell · Accepted Answer · 2011-05-08 05:44:26Z

1

Correct me if I'm wrong, but you want to get a unique ID for each user. MySQL has this feature.

answered May 8, 2011 at 5:44

Nick ODell

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