How to set a dynamic range by fixed number

Question

I am trying to set a range by a fixed number for an example.

$fixed = 5;
$value = 7;

So if my value is 7 it will be in a range from 5 to 10

I was trying the old fashion method to add + 5 to the value, but it goes out of the range. (7 + 5 = 12) and it has to be in range between 5 to 10.

$value = 19; // range in 15 to 20
$value = 23; // range in 20 to 25

Any idea?

Answer 1

This is how you can get such ranges:

function getRange(int $value, int $moduloClass = 5) {
    $start = $value - ($value % $moduloClass);
    $end = $start + $moduloClass;
    return [
        'start' => $start,
        'end' => $end
    ];
}

Explanation:

• since you may need this multiple times, we avoid duplicating the same pattern in the code and create a function (or a method) instead
• we want to find the range of the $value passed to this function
• you want ranges of $moduloClass, so $value will be equal to the greatest number divisible with $moduloClass. The reason why I made this a parameter is to allow you to choose other range sizes too if needed
• yet, the default for $moduloClass is 5, so if you do not pass a value for this parameter, it will be assumed to be 5
• We compute the remainder of the division of $value to $moduloClass and subtract the result from $value. If $value is 7 and $moduloClass is 5, then $value % $moduloClass is 2 and $value - 2 is 7 - 2 = 5, so this will be assigned to $start
• $end will equal to $start + $moduloClass, so if $start was 5, then $end will be 10
• we return an array, whose start key will be the start of the range and end key will be the end of the range

Example1

$range = getRange(7); //$moduloClass is defaulting to 5
echo "[" . $range['start'] . ", " . $range['end'] . "]";
//result will be [5, 10]

Example2

$range = getRange(345, 100);
echo "[" . $range['start'] . ", " . $range['end'] . "]";
//result will be [300, 400]