problem with decrementing counter in if loop

saco721

I am trying to get a counter to decrement within an if loop, have tried various things but it still wont work. Could you please tell me where I am going wrong.
here is the code:

<?php

for ($i=1; $i <= $num_cart_items; $i++)
{

  $test1 = "". $keyarray["item_name".$i] . ".pdf";

  if ($keyarray["quantity".$i] > 0){

  echo ("<td><font face = \"Verdana\" size = \"2\"><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</font></td>");

  $keyarray["quantity".$i]--;
  }
  else{

  echo ("<td>No downloads left</td>");
  }

}

thank you for your time!

laserlight

Please use php forum bbcode tags when posting PHP code snippets. Your code should be properly indented.
How does your code snippet not work? That is, what are the errors?

saco721

<?php

for ($i=1; $i <= $num_cart_items; $i++)
{

  $test1 = "". $keyarray["item_name".$i] . ".pdf";

  if ($keyarray["quantity".$i] > 0)
         {
            echo ("<td><font face = \"Verdana\" size = \"2\"><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</font></td>");

            $keyarray["quantity".$i]--;
         }
  else
         {
         echo ("<td>No downloads left</td>");
         }
}


?>

I hope the code is indented properly.

I do not get any error messages, the problem is that the counter $keyarray["quantity".$i]-- never decrements and hence the echo ("<td><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</td>"); always appears, no matter how many times click to download is pressed. How do I get $keyarray["quantity".$i]-- to decrement?

laserlight

I do not get any error messages, the problem is that the counter $keyarray["quantity".$i]-- never decrements and hence the echo ("<td><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</td>"); always appears, no matter how many times click to download is pressed.

Are you sure your algorithm is correct? You are looping from 1 to $num_cart_items inclusion. So, even though you are decrementing $keyarray["quantity".$i], that element is never ever reused within the loop. Consequently, the "click to download" text appears $num_cart_items times, assuming that all elements of $keyarray are greater than 0. In other words, the decrementing has nothing to do with how many times "click to download" appears.

bpat1434

Where are you getting $keyarray['quantity'.$i] from? Is it from a database or the session? If you're storing the $keyarray['quantity'.$i] anywhere, every time the script is run, it will "reset" to that higher value..

saco721

Hi
$keyarray["quantity".$i] is an array whos values come from paypal. so it should look like:

item_name quantity
item1 1 $keyarray[1]1
item2 1 $keyarray[2]1
item3 2 $keyarray[3]2

I think the above is right.
What I am trying to achieve is:
Click download and 1 download is permitted. Each time the download is made, quantity decrements by 1. If quantity is = 0, then the click download is replaced with downloads complete, which is not clickable.

I realise that the algorithm is incorrect, but am puzzled as to how it should look.

Any help would be greatly appreciated.

bpat1434

So how are you saving state between refreshes? I mean, the array is populated from paypal so it has an initial value (as you posted above). Now, when you display it decrements the local variable; however, once a link is clicked, everything is reset to what it was. Now, you'd have to use a session variable or cookie, or database to "save state" across requests.

saco721

<?php

for ($i=1; $i <= $num_cart_items; $i++)
{
session_start();
$_SESSION['quantity'] = ["quantity".$i];
$test1 = "". $keyarray["item_name".$i] . ".pdf";

  if ($_SESSION["quantity".$i] > 0)
         {
            echo ("<td><font face = \"Verdana\" size = \"2\"><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</font></td>");

            $_SESSION["quantity".$i]--;
         }
  else
         {
         echo ("<td>No downloads left</td>");
         }

}

I have never used session varibles before so please be patient. I have tried editing the algorithm to include session variables. Is it along the right lines?

bpat1434

it's along the right lines. But remember you have to have session_start(); be called before any output. Usually this means that it's best put at the very top of the script, not inside a for() loop 😉

saco721

Thanks - will try just now.

saco721

Hi!,

have tried the following code with some success.

<?php
session_start();
for ($i=1; $i <= $num_cart_items; $i++)
{

$_SESSION['quantity'] = "". $keyarray["quantity".$i] . "";
$test1 = "". $keyarray["item_name".$i] . ".pdf";

if ($_SESSION["quantity".$i] > 0)
{
echo ("<td><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</td>");

$_SESSION["quantity".$i]--;
}
else
{
echo ("<td>No downloads left</td>");
}
}

It now seems that all the downloads are complete and the 'click to download' message never appears. Instead I get 'No downloads left', even if I havent downloaded anything. Please help!

halojoy

<?php
session_start();
for ($i=1; $i <= $num_cart_items; $i++)
{
$_SESSION['quantity'] = "". $keyarray["quantity".$i] . "";
$test1 = "". $keyarray["item_name".$i] . ".pdf";

if ($_SESSION["quantity".$i] > 0)
{
echo ("<td><font face = \"Verdana\" size = \"2\"><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</font></td>");

$_SESSION["quantity".$i]--;
}
else
{
echo ("<td>No downloads left</td>");
}
}
?>

saco721 wrote:
have tried the code with some success.
It now seems that all the downloads are complete and the 'click to download' message never appears. Instead I get 'No downloads left', even if I havent downloaded anything. Please help!

I have changed 2 things in your code.

error_reporting(E_ALL) .... for Debug PHP
Because I think that code may have more than one issue, still.
changed: $SESSION['quantity'] = "". $keyarray["quantity".$i] . ""; to:
$SESSION["quantity".$i] = "". $keyarray["quantity".$i] . "";

What I feel is missing here, for more quick solution, is info.
We have no idea where $keyarray come from and what it holds.
Regards 🙂

<?php
error_reporting(E_ALL); // Debug PHP
session_start();

for ($i=1; $i <= $num_cart_items; $i++)
{
    $_SESSION["quantity".$i] = "". $keyarray["quantity".$i] . "";
    $test1 = "". $keyarray["item_name".$i] . ".pdf";

if ($_SESSION["quantity".$i] > 0)
{
    echo ("<td><font face = \"Verdana\" size = \"2\"><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</font></td>");
    $_SESSION["quantity".$i]--;
}
else
{
    echo ("<td>No downloads left</td>");
}
}
?>

bpat1434

Halojoy: read the posts you miss before you actually reply.

What I feel is missing here, for more quick solution, is info.
We have no idea where $keyarray come from and what it holds.

item_name quantity
item1 1 $keyarray[1]1
item2 1 $keyarray[2]1
item3 2 $keyarray[3]2

saco721

Error messages:

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /homepages/4/d142124103/htdocs/header.htm:5) in /homepages/4/d142124103/htdocs/end2.php on line 15

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /homepages/4/d142124103/htdocs/header.htm:5) in /homepages/4/d142124103/htdocs/end2.php on line 15

Notice: Undefined variable: header in /homepages/4/d142124103/htdocs/end2.php on line 18

Notice: Undefined offset: 1 in /homepages/4/d142124103/htdocs/end2.php on line 51

code I am using (from paypal):

<?php
// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-synch';

$tx_token = $_GET['tx'];

$auth_token = "uidZRxXdq-hJW2BG57wfPN1dZgrKS2yZV-CRUIFsjnThHr4sBhmzUloKC88";

$req .= "&tx=$tx_token&at=$auth_token";

include_once ('header.htm');

error_reporting(E_ALL);

session_start();

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('www.sandbox.paypal.com', 80, $errno, $errstr, 30);
// If possible, securely post back to paypal using HTTPS
// Your PHP server will need to be SSL enabled
// $fp = fsockopen ('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);

if (!$fp) {
// HTTP ERROR
} else {
fputs ($fp, $header . $req);
// read the body data
$res = '';
$headerdone = false;
while (!feof($fp)) {
$line = fgets ($fp, 1024);
if (strcmp($line, "\r\n") == 0) {
// read the header
$headerdone = true;
}
else if ($headerdone)
{
// header has been read. now read the contents
$res .= $line;
}
}

// parse the data
$lines = explode("\n", $res);
$keyarray = array();
if (strcmp ($lines[0], "SUCCESS") == 0) {
for ($i=1; $i<count($lines);$i++){
list($key,$val) = explode("=", $lines[$i]);
$keyarray[urldecode($key)] = urldecode($val);
}
// check the payment_status is Completed
// check that txn_id has not been previously processed
// check that receiver_email is your Primary PayPal email
// check that payment_amount/payment_currency are correct
// process payment

$firstname = $keyarray['first_name'];

$lastname = $keyarray['last_name'];

$num_cart_items = intval($keyarray['num_cart_items']);

$amount = $keyarray['mc_gross'];

$cartData = array();

for ($i=1; $i <= $num_cart_items; $i++)
{

	$_SESSION['quantity'.$i] = "". $keyarray["quantity".$i] . "";

	//echo ("<tr><td><font face = \"Verdana\" size = \"2\">" . $keyarray["option_selection1_".$i] ."</font</td>");

	//echo ("<td>&nbsp;</td>");

	//echo ("<td><font face = \"Verdana\" size = \"2\">" . $keyarray["item_name".$i]. "</font></td>"); 

	//echo ("<td>&nbsp;</td>");

		//echo ("<td align=\"center\">". $keyarray["quantity".$i] ."</td>");

	//echo ("<td>&nbsp;</td>");				

	$test1 = "". $keyarray["item_name".$i] . ".pdf";

	if ($_SESSION["quantity".$i] > 0){	

	echo ("<td><font face = \"Verdana\" size = \"2\"><a href=\"testfile.php?arg1=$test1\">Click to download.</a></font></td>");

	$_SESSION["quantity".$i]--;

	//$test2 = $_SESSION["quantity".$i];

	//echo("downloads left :$test2");		

	}

	else{

	echo ("<td>Download complete</td>");
	}

}

echo ("Your transaction has been completed, and a receipt for your purchase has been emailed to you. You may log into your account at <a href='https://www.paypal.com'>www.paypal.com</a> to view details of this transaction. ");

}
else if (strcmp ($lines[0], "FAIL") == 0) {
// log for manual investigation
}

}

fclose ($fp);

include_once ('footer.htm');

halojoy

you need to put the session_start() earlier.
At least try before
include_once ('header.htm');

Now that we have some code and some debug
some of our best men will solve this in no time.
I cant do this, because I am no good for nothing.
Regards
🙂

saco721

Hi Halojoy,

I have moved session start to the beginning of the script and the errors have reduced to 2 these are:

Notice: Undefined variable: header in /homepages/4/d142124103/htdocs/end2.php on line 18

Notice: Undefined offset: 1 in /homepages/4/d142124103/htdocs/end2.php on line 51

thank you for your help!.

bpat1434

Well, those are kinda self explanatory: You don't have a defined variable "header" (so $header isn't set) on line 18:

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";

When you first start a designation, use = not .= 😉

The second error deals with an array near line 51.

for ($i=1; $i<count($lines);$i++){
list($key,$val) = explode("=", $lines[$i]);

It's complaining about the $lines[$i] ..... not sure why though. Perhaps you have a malformed array 🙁

Also, please use php tags when you post code ...

saco721

Hi ,
I have moved session_start(); to the top of the script. This solves the following errors:

have changed $header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
to
$header = "POST /cgi-bin/webscr HTTP/1.0\r\n";

This solves the error:
Notice: Undefined offset: 1 in /homepages/4/d142124103/htdocs/end2.php on line 5.

I could not resolve the error:
Undefined variable: header in /homepages/4/d142124103/htdocs/end2.php on line 18

Im still having problems with getting the counter to decrement, I realise that the algorithm is incorrect, but I am puzzled, and really need help!. You should still have a copy of the complete script, but the part that is causing me problems is:

<?php
for ($i=1; $i <= $num_cart_items; $i++)
{
session_start();
$_SESSION['quantity'] = ["quantity".$i];
$test1 = "". $keyarray["item_name".$i] . ".pdf";

if ($_SESSION["quantity".$i] > 0)
{
echo ("<td><a href=\"testfile.php?arg1=$test1\">click to download.[/url]</td>");

$_SESSION["quantity".$i]--;
}
else
{
echo ("<td>No downloads left</td>");
}
}
?>
Am I trying to increment, then decrement by the same value, hence the value of the counter always remains the same? I realised this may have been a problem so I tried decrementing by 2 instead of one, but I still cant decrement, and the 'click to download message still appears.'

bpat1434

$SESSION['quantity'] = ["quantity".$i];

You set the max to be $SESSION['quantity'] yet you decrement $_SESSION['quantity'.$i];

Now, also note that if you "reset" this value by assigning it the value of $keyarray['quantity'.$i] every time, then your decrement feature will never work.

You should check to see if $_SESSION['quantity'.$i] is set first. If not, then assign it the default value of $keyarray['quantity'.$i]; otherwise, dont' do anything. Then in the loop, just keep decrementing the value.

if(!isset($_SESSION['quantity'.$i])) { $_SESSION['quantity'.$i] = $keyarray['quantity'.$i]; }

saco721

Hi!,

the code is now:

<?php
for ($i=1; $i <= $num_cart_items; $i++)
{
if(!isset($SESSION['quantity'.$i])) {
$SESSION['quantity'.$i] = $keyarray['quantity'.$i];
}
$test1 = "". $keyarray["item_name".$i] . ".pdf";

if ($_SESSION['quantity'.$i] > 0){

echo ("<td><a href=\"testfile.php?arg1=$test1\">Click to download.</a></td>");

$test2 = $_SESSION["quantity".$i];

$_SESSION['quantity'.$i]--;

echo("downloads left :$test2");

}
else
{
$test3 = $_SESSION["quantity".$i];

echo("downloads left :$test3");
echo ("<td>Download complete</td>");
}
}
?>

I tried adding :

{
if(!isset($SESSION['quantity'.$i])) {
$SESSION['quantity'.$i] = $keyarray['quantity'.$i];
}

It worked fine the first time, I clicked 'Click to download', it downloaded once, then returned 'Download complete'. But now I only get 'Download complete' and echo("downloads left :$test3"); only returns 0, no matter how many items I add to the shopping cart. How do I make the value 0 change to show the correct amount of downloads.
I was wondering if I has something to do with $_SESSION['quantity'.$i] not being reset. And the value of the previous session not being reset to the value of the current session?
thanks