nesbot/carbon return value

nesbot_carbon_addsub_onemonth.php

<?php
require 'vendor/autoload.php';

use Carbon\Carbon;

echo '-- add sub 1 months --', PHP_EOL;

$dt1 = Carbon::createFromDate(2011, 1, 31);
echo $dt1->toDateString(), PHP_EOL;
echo $dt1->addMonth()->toDateString(), PHP_EOL;

$dt2 = Carbon::createFromDate(2011, 3, 31);
echo $dt2->toDateString(), PHP_EOL;
echo $dt2->subMonth()->toDateString(), PHP_EOL;

echo '-- add sub 1 month with a first day of month --', PHP_EOL;

$dt3 = Carbon::createFromDate(2011, 1, 31);
echo $dt3->toDateString(), PHP_EOL;
echo $dt3->startOfMonth()->addMonth()->endOfMonth()->toDateString(), PHP_EOL;

$dt4 = Carbon::createFromDate(2011, 3, 31);
echo $dt4->toDateString(), PHP_EOL;
echo $dt4->startOfMonth()->subMonth()->endOfMonth()->toDateString(), PHP_EOL;

echo '-- leap year --', PHP_EOL;

$dt5 = Carbon::createFromDate(2016, 1, 31);
echo $dt5->toDateString(), PHP_EOL;
echo $dt5->startOfMonth()->addMonth()->endOfMonth()->toDateString(), PHP_EOL;

$dt6 = Carbon::createFromDate(2016, 3, 31);
echo $dt6->toDateString(), PHP_EOL;
echo $dt6->startOfMonth()->subMonth()->endOfMonth()->toDateString(), PHP_EOL;