Add to an array value (+1)

Question

I have an array

$hourly = array(
        "01" => "0",
        "02" => "0",
        "03" => "0",
        "04" => "0",
        "05" => "0",
        "06" => "0",
        "07" => "0",
        "08" => "0",
        "09" => "0",
        "10" => "0",
        "11" => "0",
        "12" => "0",
        "13" => "0",
        "14" => "0",
        "15" => "0",
        "16" => "0",
        "17" => "0",
        "18" => "0",
        "19" => "0",
        "20" => "0",
        "21" => "0",
        "22" => "0",
        "23" => "0"
            );

And I have a bunch of data like "01" and "03" and "21" and I want to add (+1) to that specific value in the array. So with the data set "01","03","21","01","22" the resulting array would be

$hourly = array(
        "01" => "2",
        "02" => "0",
        "03" => "1",
        "04" => "0",
        "05" => "0",
        "06" => "0",
        "07" => "0",
        "08" => "0",
        "09" => "0",
        "10" => "0",
        "11" => "0",
        "12" => "0",
        "13" => "0",
        "14" => "0",
        "15" => "0",
        "16" => "0",
        "17" => "0",
        "18" => "0",
        "19" => "0",
        "20" => "0",
        "21" => "1",
        "22" => "1",
        "23" => "0"
            );

How could I go about doing that? Is there a function to add 1 to an array element?

Answer 1

Normally, you'd be able to do:

$array["key"]++;

However, your arrays have a few peculiarities you should fix;

• Your key values are actually strings. If you want numbers you can increment, you should use numbers from the beginning. If you store a string and increment it with the syntax above, it'll be turned into an integer.
• Arrays store string or a numbers as keys. You're using both. "01" will be stored as a string key, "10" will be stored as a number. Consider storing only numbers as keys.

None of these make your script not work, but the inconsistency and unnecessary performance hit are avoidable.

Answer 2

$updates = array("01","03","21","01","22");
foreach($updates as $num) {
    $hourly[$num]++;
}