PHP - While loop

Question

print "<ul>";
foreach ($arr as $value) {
    echo("<li>" . $value[storeid] . " " . ($value[dvdstock] + $value[vhsstock]) . "</li>");
}
print "</ul>";

Will output

•2 20
•2 10
•1 20
•1 20
•1 10

I was wondering how I would adapt this loop so it outputs the total values for each &value[storeid]

•1 50
•2 30

Thanks very much :)

Answer 1

Correct version:

<?php

$initial = array (
    array (
        'id'     => 1,
        'amount' => 10
    ),
    array (
        'id'     => 1,
        'amount' => 10
    ),
    array (
        'id'     => 2,
        'amount' => 20
    ),
    array (
        'id'     => 2,
        'amount' => 20
    ),
    array (
        'id'     => 2,
        'amount' => 20
    ),
);

$result = array ();

foreach ($initial as $value) {
    $result[$value['id']] += $value['amount'];
}

print_r($result);

?>

Answer 2

Use another array to calculate the values you want:

// setup a quick place to store the data
$stores = array();
foreach ($arr as $value) {
  $stores[$value['storeid']] += $value['dvdstock'] + $value['vhsstock'];
}
print "<ul>";
// loop through the new data
foreach ($stores as $id => $value) {
    echo("<li>" . $id . " " . ($value) . "</li>");
}
print "</ul>";

Answer 3

If you are getting the data from an SQL database then you should do this using SUM() functions in the SQL as it is more efficient. If the data source is from somewhere else you should do something like this:

//Sum data
foreach ($arr as $value) {
$sums[{$value[storeid]}] += ($value[dvdstock] + $value[vhsstock]);
}

print "<ul>";
foreach ($sums as $key => $sum) {
    echo("<li>$key $sum</li>");
}
print "</ul>";

Answer 4

<?php
$sums = array();
foreach ($arr as $value)
{
    $sums[$value['storeid']] += $value['dvdstock'];
}
print_r($sums);
?>

Answer 5

It is a for loop and you have to make two of them. First to compute the sum and then to iterate over these values:

$data = array();

foreach ($arr as $value) {
    $data[$value['storeid']] += $value['dvdstock'] + $value['vhsstock'];
}


print "<ul>";
foreach ($data as $storeid => $sum) {
    echo('<li>' . $storeid . ' ' . ($sum) . '</li>');
}
print "</ul>";

Btw one word about strings:
Either use single quotes ' with concatenation .: 'foo: ' . $bar.
Or double quotes " and put the variables inside the string: "foo: $bar".