variable variable name

[Anon]

I looked in the PHP manual under Variable variables, but I don't think that's what I'm trying to do.

Here's the code

$track_result = mysql_query ("SELECT * FROM recordings WHERE recid= '$row["track$trackno"]' );
$track_row = mysql_fetch_array($track_result);

for ($trackno = 1 || $trackno++)
{
[print some info for this track]
}

You see I want to select * from recordings where recid='$row["track1,track2,etc"]'. $row ["track1"] and so on were already defined earlier.

How can I stick the $trackno variable into $row["track$trackno"]?

Or is the problem that I'm declaring $trackno after I defined $track_result?

I'm a newbie to PHP if you couldn't tell. Any help would be much appreciated.

Duncan

[[deleted]]

Hmm well obviously you can't ever use a variable untill you have defined it's value.
So on your query, PHP will assume $trackno to be empty, and fetch only the rows where trackid="track".

You have to tell your SQL query which tracks to select by mentioning all trackid's that qualify:
select * from table where trackid in ('track1','track2','track34');

BTW it would probably be easier if you changed trackid into an integer, so you can just call it "1" instead of "track1". Then, you can also select tracks 1 through 6:
select * from table where track<7 and track >0;

[Anon]

Thanks for the help.

Part of the problem is that I never know which, if any, track# columns will contain data for a row. So I had something like this:

if ( $track_result == 0 )
{
break;
}

If no data, then skip that one and go to the next one, track#+1.

Anyway, you're right, I'll change the track# columns into just integers and make it simple.

Thanks again,
Duncan

[Anon]

Hello Vincent and Duncan, i have a similar trouble. I understand the solution you gave to Duncan, but in the case the variable was defined, is the sintaxis "$someting$thatChanges" alright?

this is a part of my code:

$i=1;
while ($i<=$bars):
$parts_gen_v_prepol$i=explode ("@", $gen_v_prepol$i);
$gen_v_com$i=Polar ($parts_gen_v_prepol$i[0],$parts_gen_v_prepol_$i[1]);`
$i++;
endwhile;

I'm receiving a ($bars) number of data called $parts_gen_v_prepol_1, 2, and so on. And then i'm processing it with an explode and converting to $gen_v_com_1, 2, 3, through a custom function Polar(). The thing is it doesn't seem to understand the mixing: $gen_v_com$i. I tried with $gen_v_com_{$i}, but it doesn't work anyway.

Well, if you can help me or tell me some reference, many many thanks.

[[deleted]]

The correct use of variable variables is:

error_reporting(E_ALL);
$gen_com_2 = 'hello';
$sBasename = 'gen_com_';
$sExtention = '2';

// Put the new var name in curlybrackets:
echo ${$sBasename . $sExtention};

// Or create a var containing the new name, and use the double-dollarsign:
$sNewVarName = $sBasename . $sExtention;
echo $$sNewVarName;

[Anon]

Thanks Vincent, i think that helps me.

I was trying something like this, but in the wrong way because when i echo the new variable i just got the new name, not the content....

Carlos Palol
[e-mail]