Get date for Monday and Friday for the current week

How can I get the date for Monday and Friday for the current week?

I have the following code, but it fails if current day is Sunday or Saturday.

$current_day = date("N");
$days_to_friday = 5 - $current_day;
$days_from_monday = $current_day - 1;
$monday = date("Y-m-d", strtotime("- {$days_from_monday} Days"));
$friday = date("Y-m-d", strtotime("+ {$days_to_friday} Days"));

Assuming your week starts on Monday you can use DateTime class with specific relative formats.

To get the Monday and Friday for the current week:

$mondayThisWeek = new DateTimeImmutable("monday this week");
$fridayThisWeek = new DateTimeImmutable("friday this week");

// so when current date is Sun, 07 Jan 2024
// $mondayThisWeek will be Mon, 01 Jan 2024
// $fridayThisWeek will be Fri, 05 Jan 2024

To get Monday and Friday relative to a specific date:

$referenceDate = new DateTimeImmutable("2024-01-07");
$thatMonday = $referenceDate->modify("monday this week");
$thatFriday = $referenceDate->modify("friday this week");

// $thatMonday will be Mon, 01 Jan 2024
// $thatFriday will be Fri, 05 Jan 2024

If your week starts on (for example) Sunday then you will have to calculate Monday and Friday manually. Here is an example:

$referenceDate = new DateTimeImmutable("2024-01-07");
$dayOfWeek = (int) $referenceDate->format("w");
// 0 = Sun
// 1 = Mon
// 2 = Tue
// 3 = Wed
// 4 = Thu
// 5 = Fri
// 6 = Sat

if ($dayOfWeek === 0) {
    $mondayModifier = "next monday";
} elseif ($dayOfWeek === 1) {
    $mondayModifier = "today";
} else {
    $mondayModifier = "previous monday";
}

if ($dayOfWeek < 5) {
    $fridayModifier = "next friday";
} elseif ($dayOfWeek === 5) {
    $fridayModifier = "today";
} else {
    $fridayModifier = "previous friday";
}

$thatMonday = $referenceDate->modify($mondayModifier);
$thatFriday = $referenceDate->modify($fridayModifier);

// $thatMonday will be Mon, 08 Jan 2024
// $thatFriday will be Fri, 12 Jan 2024