PHP: loop to create list of previous 12 months

问题

is there a way I can use a PHP loop to create a list like the following with the previous 12 months, based on the current month (excluding the current month) ? The value should always be the first of the month (format: yyyy-mm-dd) and the dropdown itself should just show year and month (format: yyyy-mm):

<option value="2014-03-01">2014-03</option>
<option value="2014-02-01">2014-02</option>
<option value="2014-01-01">2014-01</option>
<option value="2013-12-01">2013-12</option>
<option value="2013-11-01">2013-11</option>
<option value="2013-10-01">2013-10</option>
//...

I tried the following but seem to have something wrong there as this is not working:

<?php for ($i=0; $i<=12; $i++) { ?>
    <option value="<?php echo date('Y-m-d', strtotime("-1 month")); ?>"><?php echo date('Y-m', strtotime("-1 month")); ?></option>
<? } ?>

Many thanks for any help with this, Tim.

回答1:

<?php
for ($i=0; $i<=12; $i++) { 
echo '<option value="'.date('Y-m-d', strtotime("-$i month")).'">'.date('Y-m', strtotime("-$i month")).'</option>';
 }

回答2:

$start    = (new DateTime('1 year ago'))->modify('first day of this month');
$end      = (new DateTime())->modify('first day of this month');
$interval = new DateInterval('P1M');
$period   = new DatePeriod($start, $interval, $end);

$months = array();
foreach ($period as $dt) { 
    $months[$dt->format('Y-m-d')] = $dt->format('Y-m');
}
$reverse_months = array_reverse($months);
print_r($reverse_months);

Demo

You can then loop through $reverse_months to create your dropdown

foreach($reverse_months as $key => $value) {
?>
    <option value="<?php echo key; ?>"><?php echo value; ?></option>
<?php
}

The reason why we have to use array_reverse() is DatePeriod only goes forward in time.

回答3:

You can use the datetime extension to create an iterator. It is quite simple:

// This is when to start counting
$start = new DateTime('now');

// The interval; i.e. every time we iterate we should get
// the first day of the previous month
$interval = DateInterval::createFromDateString('first day of last month');

// The period (or the iterator) should go for twelve
// months and the start date should not be included
$period = new DatePeriod($start, $interval, 12, DatePeriod::EXCLUDE_START_DATE);

// The DatePeriod class implements the Traversable
// interface and can therefore be used in a foreach loop
foreach($period as $time) {
    $val = $time->format("Y-m-d");
    $txt = $time->format("Y-m");
    echo "<option value=\"{$val}\">{$txt}</option>\n";
}

回答4:

This is what I have used, it's a bit rudimentary but works even when you get to the end of the month .. unlike the accepted answer as Glavić pointed out:

<?php
$year = date("Y");
$month = date("m");
for ($i=0; $i<=12; $i++)
{
    $month--;
    if ($month < 1) { $month = 12; $year--; }
    echo '<option value="'.date('Y-m-d', strtotime($year."-".$month."-01")).'">'.date('Y-m', strtotime($year."-".$month."-01")).'</option>';
}

回答5:

Change -1 to $i to reflect and store it for double use.

<?php 
    for ($i=1; $i>=12; $i++) { 
        $last = strtotime("-$i month");
?>
    <option value="<?php echo date('Y-m-d', $last);?>"><?php echo date('Y-m', $last);?></option>
 <? } ?>

来源：https://stackoverflow.com/questions/22847579/php-loop-to-create-list-of-previous-12-months

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