Calculate business days

Question

I need a method for adding \"business days\" in PHP. For example, Friday 12/5 + 3 business days = Wednesday 12/10.

At a minimum I need the code to understand weekend

Answer 1

My version based on the work by @mcgrailm... tweaked because the report needed to be reviewed within 3 business days, and if submitted on a weekend, the counting would start on the following Monday:

function business_days_add($start_date, $business_days, $holidays = array()) {
    $current_date = strtotime($start_date);
    $business_days = intval($business_days); // Decrement does not work on strings
    while ($business_days > 0) {
        if (date('N', $current_date) < 6 && !in_array(date('Y-m-d', $current_date), $holidays)) {
            $business_days--;
        }
        if ($business_days > 0) {
            $current_date = strtotime('+1 day', $current_date);
        }
    }
    return $current_date;
}

And working out the difference of two dates in terms of business days:

function business_days_diff($start_date, $end_date, $holidays = array()) {
    $business_days = 0;
    $current_date = strtotime($start_date);
    $end_date = strtotime($end_date);
    while ($current_date <= $end_date) {
        if (date('N', $current_date) < 6 && !in_array(date('Y-m-d', $current_date), $holidays)) {
            $business_days++;
        }
        if ($current_date <= $end_date) {
            $current_date = strtotime('+1 day', $current_date);
        }
    }
    return $business_days;
}

As a note, everyone who is using 86400, or 24*60*60, please don't... your forgetting time changes from winter/summer time, where a day it not exactly 24 hours. While it's a little slower the strtotime('+1 day', $timestamp), it much more reliable.