既然没人提到这一点，这里有另一种方法:

$date = date_create_from_format("m-d-Y", "10-16-2003")->format("Y-m-d");

您需要小心使用m/d/Y和m-d-Y格式。PHP认为/表示m/d/Y， -表示d-m-Y。在这种情况下，我将显式地描述输入格式:

$ymd = DateTime::createFromFormat('m-d-Y', '10-16-2003')->format('Y-m-d');

这样你就不会因为某个解释而心血来潮。

要解析日期，你应该使用: DateTime: createFromFormat ();

Ex:

$dateDE = "16/10/2013";
$dateUS = \DateTime::createFromFormat("d.m.Y", $dateDE)->format("m/d/Y");

但是，要小心，因为这会崩溃:

PHP Fatal error: Call to a member function format() on a non-object 

你实际上需要检查格式是否正常，首先:

$dateDE = "16/10/2013";
$dateObj = \DateTime::createFromFormat("d.m.Y", $dateDE);
if (!$dateObj)
{
    throw new \UnexpectedValueException("Could not parse the date: $date");
}
$dateUS = $dateObj->format("m/d/Y");

现在你将得到一个异常，而不是崩溃，你可以捕获，传播，等等。

$dateDE格式错误，应该是“16.10.2013”;

如果你希望接受日期使用美式排序(月，日，年)的欧式格式(使用破折号或句号作为日，月，年)，同时仍然接受其他格式，你可以扩展DateTime类:

/**
 * Quietly convert European format to American format
 *
 * Accepts m-d-Y, m-d-y, m.d.Y, m.d.y, Y-m-d, Y.m.d
 * as well as all other built-in formats
 * 
 */
class CustomDateTime extends DateTime 
{
  public function __construct(string $time="now", DateTimeZone $timezone = null) 
  {
    // convert m-d-y or m.d.y to m/d/y to avoid PHP parsing as d-m-Y (substr avoids microtime error)
    $time = str_replace(['-','.'], '/', substr($time, 0, 10)) . substr($time, 10 );

    parent::__construct($time, $timezone);
  }
}

// usage:
$date = new CustomDateTime('7-24-2019');
print $date->format('Y-m-d');

// => '2019-07-24'

或者，你可以让一个函数接受m-d-Y并输出Y-m-d:

/**
 * Accept dates in various m, d, y formats and return as Y-m-d
 * 
 * Changes PHP's default behaviour for dates with dashes or dots.
 * Accepts:
 *   m-d-y, m-d-Y, Y-m-d,
 *   m.d.y, m.d.Y, Y.m.d,
 *   m/d/y, m/d/Y, Y/m/d,
 *   ... and all other formats natively supported 
 * 
 * Unsupported formats or invalid dates will generate an Exception
 * 
 * @see https://www.php.net/manual/en/datetime.formats.date.php PHP formats supported
 * @param  string $d various representations of date
 * @return string    Y-m-d or '----' for null or blank
 */
function asYmd($d) {
  if(is_null($d) || $d=='') { return '----'; }

  // convert m-d-y or m.d.y to m/d/y to avoid PHP parsing as d-m-Y
  $d = str_replace(['-','.'], '/', $d);

  return (new DateTime($d))->format('Y-m-d');
}

// usage:

<?= asYmd('7-24-2019') ?>

// or

<?php echo asYmd('7-24-2019'); ?>

如果您的日期格式为“07/May/2018”，并需要将其改为“2018-05-07”，以便与MySQL兼容，您可以使用:

if (!empty($date)) {
  $timestamp = strtotime($date);
  if ($timestamp === FALSE) {
    $timestamp = strtotime(str_replace('/', '-', $date));
  }
  $date = date('Y-m-d', $timestamp);
}

$d = new DateTime('10-16-2003');

$timestamp = $d->getTimestamp(); // Unix timestamp
$formatted_date = $d->format('Y-m-d'); // 2003-10-16

编辑:您还可以将DateTimeZone传递给DateTime()构造函数，以确保创建所需时区的日期，而不是服务器默认的日期。