Carbon: Frequently asked questions

Carbon-Frequently-asked-questions.md

Carbon: Frequently asked questions

Q001-Details-needed.md

Some informations we ask in our issue template are missing, to get support please ensure to give at least:

• your Carbon version;
• your PHP version;
• a minimal code chunk to reproduce your case;
• the current output of this code;
• the output you expect.

Thanks.

Q002-Add-sub month-year overflow.md

From the documentation (https://carbon.nesbot.com/docs/#api-addsub):

By default, Carbon relies on the underlying parent class PHP DateTime behavior. As a result adding or subtracting months can overflow, example:

$dt = Carbon::create(2017, 1, 31, 0);

echo $dt->copy()->addMonth();            // 2017-03-03 00:00:00
echo $dt->copy()->subMonths(2);          // 2016-12-01 00:00:00

You can prevent the overflow with Carbon::useMonthsOverflow(false)

Carbon::useMonthsOverflow(false);

$dt = Carbon::createMidnightDate(2017, 1, 31);

echo $dt->copy()->addMonth();            // 2017-02-28 00:00:00
echo $dt->copy()->subMonths(2);          // 2016-11-30 00:00:00

// Call the method with true to allow overflow again
Carbon::resetMonthsOverflow(); // same as Carbon::useMonthsOverflow(true);

The method Carbon::shouldOverflowMonths() allows you to know if the overflow is currently enabled. You also can use ->addMonthsNoOverflow, ->subMonthsNoOverflow, ->addMonthsWithOverflow and ->subMonthsWithOverflow (or the singular methods with no s to "month") to explicitly add/sub months with or without overflow no matter the current mode.

Carbon::useMonthsOverflow(false);

$dt = Carbon::createMidnightDate(2017, 1, 31);

echo $dt->copy()->addMonthWithOverflow();          // 2017-03-03 00:00:00
// plural addMonthsWithOverflow() method is also available
echo $dt->copy()->subMonthsWithOverflow(2);        // 2016-12-01 00:00:00
// singular subMonthWithOverflow() method is also available
echo $dt->copy()->addMonthNoOverflow();            // 2017-02-28 00:00:00
// plural addMonthsNoOverflow() method is also available
echo $dt->copy()->subMonthsNoOverflow(2);          // 2016-11-30 00:00:00
// singular subMonthNoOverflow() method is also available

echo $dt->copy()->addMonth();                      // 2017-02-28 00:00:00
echo $dt->copy()->subMonths(2);                    // 2016-11-30 00:00:00

Carbon::useMonthsOverflow(true);

$dt = Carbon::createMidnightDate(2017, 1, 31);

echo $dt->copy()->addMonthWithOverflow();          // 2017-03-03 00:00:00
echo $dt->copy()->subMonthsWithOverflow(2);        // 2016-12-01 00:00:00
echo $dt->copy()->addMonthNoOverflow();            // 2017-02-28 00:00:00
echo $dt->copy()->subMonthsNoOverflow(2);          // 2016-11-30 00:00:00

echo $dt->copy()->addMonth();                      // 2017-03-03 00:00:00
echo $dt->copy()->subMonths(2);                    // 2016-12-01 00:00:00

Carbon::resetMonthsOverflow();

From version 1.23.0, overflow control is also available on years.