PHP: Calculate with decimals

Question

I am creating an app which calculates nutrients of food based on a specific amount. The user fills in the amount of food they have consumed and the app calculates the nutrient values.

My source data has values with decimals, for example: 100g of strawberries have 6,5 carbs.

When I fill in 100g of strawberries (which is the same amount of grams as the source data) the app will output 6 instead of 6,5. So it seems like my calculations ignore everything that's behind the comma (",").

My code:

$con = mysqli_connect('localhost','root','','food');
if (!$con) {
    die('Could not connect: ' . mysqli_error($con));
}

mysqli_select_db($con, "food");
$sql = "SELECT * FROM products WHERE id = '".$q."'";
$result = mysqli_query($con, $sql);

if ($result->num_rows > 0) {
    while($row = mysqli_fetch_array($result)) {
        $GLOBALS['name'] = $row['product'];
        $GLOBALS['kcal'] = $row['kcal'] / 100 * $GLOBALS['amount'];
        $GLOBALS['protein'] = $row['protein'] / 100 * $GLOBALS['amount'];       
        $GLOBALS['fat'] = $row['fat'] / 100 * $GLOBALS['amount'];       
        $GLOBALS['carbs'] = $row['carbs'] / 100 * $GLOBALS['amount'];
    }
} else {
    echo "Geen gegevens";
}

If I use number_format around the equation, the results will still be wrong (output will be 6).

What am I doing wrong?

Demo

Fill in the top two inputs:

Strawberries (Aardbeien)

100

Click "Voeg toe"

Alex M · Accepted Answer · 2016-08-10 09:46:57Z

2

Maybe, you need use str_replace function? For example:

$GLOBALS['kcal'] = str_replace(',','.',$row['kcal']) / 100 * $GLOBALS['amount'];

edited Aug 10, 2016 at 9:46

Alex M

2,8467 gold badges31 silver badges36 bronze badges

answered Aug 10, 2016 at 9:15

he11d0g

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