php problem having the sum of values in a loop - php

Question

I'm new in php and got stuck doing a loop.
I have the following:
an array containing 0 or not named $receivers.
another array containing total of receivers which is a number, named $totalreceivers.
a function querying a table with the id, returning 0 or number, named status().
I want to loop through each status() of the receivers and show the sum at the end. I couldn't get it.
Any help will be appreciated. Thanks in advance.
Here is what I tried:
for ($i = 0; $i < $totalreceivers; $i++)
{
$status = status($receivers[$i]);
foreach ($totalreceivers as $value)
$status = status($receivers[$i]);
echo "the sum of receiver having status different than 0 is";
echo count($status);
}
function status($id)
{
global $dbhost;
global $dbuser;
global $dbpass;
global $dbname;
global $d1;
$q2 = mysql_query("select * from user where id ='$id' AND subscription_end_date IS NULL", $d1);
while($row2 = mysql_fetch_array($q2))
$rowservice = $row2['value'];
return $rowservice;
}

Answer 1

A couple things in your code don't really make sense. First, you're trying to iterate through $totalreceivers twice, one loop being nested in the other. I doubt that's what you want so you should get rid of one of them. And your first loop has a bad expression: to iterate through $totalreceivers in your first for loop, you need to have your testing expression go against the number of elements in the array and not the array itself (can use count()): for ($i = 0; $i < count($totalreceivers); $i++).
Second, you're resetting the value of $status each time you call status() in your loop. To add to it, use the += operator: $status += status($receivers[$i]);
Third, you're doing the same in status() function with $rowservice; resetting it each iteration of that while loop. Either set it once, or sum it up.

Answer 2

You can simplify this task by letting MySQL do more of the work for you.
You have an array $receivers which presumably contains id's for subscribers to (receivers of) something. (I may use receiver and subscriber interchangeably.)
The status() function retrieves from the database the value for each receiver where the subscription_end_date is null. I am going to assume that there is only one row per subscriber because you only return the last result via the variable $rowservice.
It's unclear from your code if you want a count of receivers with a value other than 0, or if you want a sum of all non-zero values. The question then is:
Do you want to know how many subscribers have nonzero values? or,
Do you want to know the sum of all values for subscribers with nonzero values?
Fortunately both of these can be easily found:
How many receivers have non-zero values?
$allreceivers = implode(',', $receivers);
$query = "SELECT COUNT(id) AS total_receivers
FROM user
WHERE subscription_end_date IS NULL
AND value != 0
AND id IN ($allreceivers);";
$result = mysql_query($query, $d1);
$row = mysql_fetch_array($result);
$total_receivers = $row['total_receivers'];
echo "The number of receivers having status (value) other than 0 is $total_receivers";
What is the sum of all receiver values?
$allreceivers = implode(',', $receivers);
$query = "SELECT SUM(value) AS receiver_value_sum
FROM user
WHERE subscription_end_date IS NULL
AND id IN ($allreceivers);";
$result = mysql_query($query, $d1);
$row = mysql_fetch_array($result);
$receiver_value_sum = $row['receiver_value_sum'];
echo "The sum of receiver values is $receiver_value_sum";

Answer 3

At first glance, it looks like you are just overwriting "$status" on each iteration. Before the loop starts, set $status to an empty array and then add to it on each iteration. For example:
$status = array();
foreach ( $totalreceivers as $value)
{
$status[] = status($receivers[$i]);
}
echo count($status);

Answer 4

I will try to outline some possible problems with your code below:
for ($i = 0; $i < $totalreceivers; $i++) { //This open bracket has no end bracket
/*I assume total receivers is the number of receivers; if that is the case, it shouldn't be an array, but merely a value.*/
$status = status($receivers[$i]);
/*I think you should define the status function before you call it; also, if you are just calling the status function for each value of $receivers, why don't you just do a foreach($receivers as $value) loop, like you did below with $totalreceivers. */
foreach ( $totalreceivers as $value)
/*I'm not sure what $totalreceivers is. You said its an array containing total number of receivers; again, I would think this would be a single value, and not an array*/
{
$status = status($receivers[$i]);
/*looks like you're calling the status function again*/
}
echo "the sum of receiver having status different thant 0 is"; echo count($status);
/* $status at this point would count the value from row2 for the last value in $receivers, and not a count of array values. Perhaps you could do $status[] = status($receivers[$i]), and then count($status) to save each value to an array, then count the elements. */
function status($id){
global $dbhost;
global $dbuser;
global $dbpass;
global $dbname;
/* The values above aren't used in the function; you may want to connect to the database outside of the function, before the foreach loop. */
global $d1 ;
$q2 = mysql_query("select * from user where id ='$id' AND subscription_end_date IS NULL",$d1);
while($row2 = mysql_fetch_array($q2)){
$rowservice = $row2['value'];
}
return $rowservice;
}
/*the rest looks good*/