Increase days to php current Date()

Question

php supports c style date functions. You can add or substract date-periods with English-language style phrases via the strtotime function. examples...

$Today=date('y:m:d');

// add 3 days to date
$NewDate=Date('y:m:d', strtotime('+3 days'));

// subtract 3 days from date
$NewDate=Date('y:m:d', strtotime('-3 days'));

// PHP returns last sunday's date
$NewDate=Date('y:m:d', strtotime('Last Sunday'));

// One week from last sunday
$NewDate=Date('y:m:d', strtotime('+7 days Last Sunday'));

or

<select id="date_list" class="form-control" style="width:100%;">
<?php
$max_dates = 15;
$countDates = 0;
while ($countDates < $max_dates) {
    $NewDate=Date('F d, Y', strtotime("+".$countDates." days"));
    echo "<option>" . $NewDate . "</option>";
    $countDates += 1;
}
?>

a day is 86400 seconds.

$tomorrow = date('y:m:d', time() + 86400);

The simplest way to add x no. of days..

echo date('Y-m-d',strtotime('+1 day'));    //+1 day from today

OR from specified date...

echo date('Y-m-d',strtotime('+1 day', strtotime('2007-02-28')));

With php 5.3

    $date = new DateTime();
    $interval = new DateInterval('P1D');
    echo $date->format('Y-m-d') , PHP_EOL;
    $date->add($interval);
    echo $date->format('Y-m-d'), PHP_EOL;
    $date->add($interval);
    echo $date->format('Y-m-d'), PHP_EOL;

will output

2012-12-24

2012-12-25

2012-12-26

The date_add() function should do what you want. In addition, check out the docs (unofficial, but the official ones are a bit sparse) for the DateTime object, it's much nicer to work with than the procedural functions in PHP.

If you need this code in several places then I'd suggest that you add a short function to keep your code simpler and easier to test.

function add_days( $days, $from_date = null ) {
    if ( is_numeric( $from_date ) ) { 
        $new_date = $from_date; 
    } else { 
        $new_date = time();
    }

    // Timestamp is the number of seconds since an event in the past
    // To increate the value by one day we have to add 86400 seconds to the value
    // 86400 = 24h * 60m * 60s
    $new_date += $days * 86400;

    return $new_date;
}

Then you can use it anywhere like this:

$today       = add_days( 0 );
$tomorrow    = add_days( 1 );
$yesterday   = add_days( -1 );
$in_36_hours = add_days( 1.5 );

$first_reminder  = add_days( 10 );
$second_reminder = add_days( 5, $first_reminder );
$last_reminder   = add_days( 3, $second_reminder );

$NewDate=Date('Y-m-d', strtotime('+365 days'));

echo $NewDate; //2020-05-21