For Loop - for loop problem

adly3000

Feb 22 2006, 02:56 PM

i'd like to make for loop which dependes on a $_GET variable:

here is my tries:

CODE

if (isset($_GET['date'])
{
switch($_GET['date'])
    {
        case 'asc':
$exp1 = "$x>0";
$exp2 = "$x=$total";
            $condition = '$x++';
            break;
        case 'desc';
$exp1 = "$x=$total";
$exp2 = "$x>0";
            $condition = '$x--';
            break;
    }
}

then

CODE

for($exp1; $exp2; $condition)
{
//** do something **//
}

that is what i want to do, sure this code is wrong so what is the valid code?!!

Spectre

Feb 23 2006, 01:44 AM

Although I wouldn't recommend it, you could use something like:

CODE

eval($exp1.';');
while( eval('return '.$exp2.';') ) {
/* Do something */
eval($condition.';');
}

This will, essentially, perform the same as a for() loop.

agentredeye

Feb 23 2006, 04:10 AM

can i ask something for for loop..

can you make me a program on how to make a program about PALINDROME

using for loop and array.......

thanks..

just pm the code plsss...

i need it badly....

Tyssen

Feb 23 2006, 06:03 AM

QUOTE(agentredeye @ Feb 23 2006, 02:10 PM)

i need it badly....

If you need it that badly, maybe you should pay someone to do it for you.

no9t9

Feb 24 2006, 03:10 AM

trying to do what you want is not difficult but it is not a good way to code. It is better to use logic to get things done... also, Personally, I don't like switch statements, why not just keep it simple and use if statement for only 2 conditions.

one other thing, assuming what you did works... you would have for(x>0,x=total,x++) and for(x=total,x>0,x--) ... that first for loop doesn't work... I am assuming you wanted for(x=0, x<total,x++). This is what you should do.

CODE

if ($_GET['date'] == 'asc') { $i = 0; $j = $total }
else if ($_GET['date'] == 'desc') {$i = -$total; $j = $0 }
for ($x=$i;$x<$j;$x++) { do stuff }

If you are actually using the count down counter for something just switch the sign (from neg to pos).

QUOTE(adly3000 @ Feb 22 2006, 09:56 AM)

i'd like to make for loop which dependes on a $_GET variable:

here is my tries:

CODE

then

CODE

for($exp1; $exp2; $condition)
{
//** do something **//
}

that is what i want to do, sure this code is wrong so what is the valid code?!!

adly3000

Feb 24 2006, 10:32 PM

thanks no9t9;

CODE

if ($_GET['date'] == 'asc') { $i = 0; $j = $total }
else if ($_GET['date'] == 'desc') {$i = -$total; $j = $0 }
for ($x=$i;$x<$j;$x++) { do stuff }

this helps alot, that is the the same as:

CODE

$start = 0;
$end = $total;
$step = 1;

if (isset($_GET{"date"}) && $_GET{"date"} == "desc") {
   $start = $total;
   $end = 0;
   $step = -1;
}

for ($x = $start; $x <= $end; $x += $step) {
// something
}

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