PHP Carbon class changing my original variable value

When you run these methods against a Carbon object it updates the object itself. Therefore addDay() moves the value of Carbon one day forward.

Here's what you need to do:

$now = Carbon::now();$now->copy()->addDay();$now->copy()->addMonth();$now->copy()->addYear();// etc...

The copy method essentially creates a new Carbon object which you can then apply the changes to without affecting the original $now variable.

To sum up, the methods for copying a Carbon instance are:

• copy
• clone - an alias of copy

Check out the documentation: https://carbon.nesbot.com/docs/

The problem is that you're assuming that subDay()/addDay() don't change the date object, whereas they do.... they're just wrapping around the DateTime object modify() method:

DateTime::modify -- date_modify — Alters the timestamp

(my emphasis)

Instead, use

$navDays = [    '-7Days' => (clone $date)->subDay('7')->toDateString(),    '-1Day'  => (clone $date)->subDay('1')->toDateString(),    'Today'  => (clone $date)->today()->toDateString(),    '+1Day'  => (clone $date)->addDay('1')->toDateString(),    '+7Days' => (clone $date)->addDay('7')->toDateString()];

Doco says

You can also create a copy() of an existing Carbon instance. As expected the date, time and timezone values are all copied to the new instance.

$dt = Carbon::now();echo $dt->diffInYears($dt->copy()->addYear());  // 1// $dt was unchanged and still holds the value of Carbon:now()