How to mutiply all values in a PHP foreach array

Question

i want to mutiply all the values in a foreach array by itself

here is an example of the array Array ( [0] => 2.4 [1] => 6 ) , all i want to do is mutiply 2.4*6

foreach($pp_events as $key=>$value)
{
#echo $value;
$pick=mysql_query("select * from pick where eventid='$value'");
$row=mysql_fetch_array($pick);
$sum*=$row['startPrice'];

}

@JohnConde That question is about multiplying each element by a constant, not multiplying them by each other. — Barmar, Feb 14 '14 at 20:05
You could do this in sql if you wanted, http://stackoverflow.com/questions/8223057/multiply-2-rows-in-sql — Lawrence Cherone, Feb 14 '14 at 20:08
i want to be able to multiply them by each other not using a constant — Josieboy Ajose, Feb 14 '14 at 20:09

score 4 · Answer 1 · edited May 23 '17 at 11:49

There's no need to implement this yourself. PHP has a built-in function for multiplying all the values in an array - array_product(). Use that instead:

$products = array();
foreach ($pp_events as $key => $value) {
    $pick = mysql_query("select * from pick where eventid='$value'");
    $row = mysql_fetch_array($pick);
    $products[] = $row['startPrice'];
}

echo array_product($products);

See also:

Why shouldn't I use mysql_* functions in PHP?

score 0 · Accepted Answer · answered Feb 14 '14 at 20:08

You need to initialize the variable to 1, then your loop should work.

$product = 1;
foreach ($pp_events as $key => $value) {
    $pick = mysql_query("select * from pick where eventid='$value'");
    $row = mysql_fetch_array($pick);
    $product *= $row['startPrice'];
}
echo $product;

You can also do a single query, instead of a separate query for each value:

$events = implode(',', array_map(function($x) { return "'$x'"; }, $pp_events));
$pick = mysql_query("select startPrice from pick where eventid IN ($events)");
$product = 1;
while ($row = mysql_fetch_assoc($pick)) {
    $product = $row['startPrice'];
}
echo $product;

How to mutiply all values in a PHP foreach array

2 Answers2