PHP - Summing an array of decimal values

Question

I'm trying to calculate the sum of an array of decimal values in PHP, but for some reason it keeps rounding to integers.

for example:

$oldArray = array(0.00,1000.11,988.92,978.22,964.01,953.07,948.82,917.26,902.56,913.21,904.08,898.86,892.79);
$myVar = 0.0;
for($k=1;$k<10;$k++)
{
$myVar += $oldArray[$k];
}
print_r($myVar);

$oldArray is actually populated with decimal values from an SQL query (the length of $oldarray is about several hundred, but I want the first 10. In the above example, I'm expecting $myVar to be a decimal, but it turns out to be just an integer. I tried setting $myVar = 0.0000 before the for loop, I tried $myVar += $oldArray[$k] + 0.0000, etc but nothing seems to work.

What am I doing wrong? How do I explicitly set $myVar to be a decimal?

Answer 1

Can't reproduce this.

php > $oldArray = array(0, .1, .2, .3, .4, .5, .6, .7, .8, .9);                                                    
php > $myVar = 0.0;
php > for($k=0;$k < count($oldArray);$k++)
php > {
php { $myVar += $oldArray[$k];
php { }
php > print_r($myVar);
4.5

EDIT: I tried the code in your comment, and it's fine. Like AlbertoPL, I suspect the problem is elsewhere.

php > $oldArray = array(0.01,1000.11,988.92,978.22,964.01,953.07,948.82,917.26,902.56,913.21,904.08,898.86,892.79);
php > $myVar = 0.0000;
php > for($k=1;$k<10;$k++)
php >   $myVar += $oldArray[$k];
php > print_r($myVar);
8566.18

Answer 2

You can try using array_sum() instead and use (float) to cast the values. Additionally I would make sure that the values in the array are in the correct format (1.45 and not 1,45). HTH.

Update

Btw. you can use "is_float()" to check every parameter in the array.

Answer 3

Given that this seems impossible to reproduce, to me it sounds like a problem with your PHP environment itself.

Check php.ini for a setting called "precision", and make sure it's set to the default of 14 significant figures. I can't imagine why this would be changed, but it would definitely have an impact.

Answer 4

Use array_chunk() and array_sum()

Answer 5

I know that this has already been answered, but if you are trying to sum values from MySQL, I would suggest this as an often fastest alternative:

SELECT SUM( `column_name` ) FROM `table_name` LIMIT 10;