如果您知道格式，请使用strptime，因为strtotime会对格式进行猜测，这可能并不总是正确的。由于strptime没有在Windows中实现，所以有一个自定义函数

http://nl3.php.net/manual/en/function.strptime.php#86572

记住，返回值tm_year来自1900!tm_month是0-11

例子:

$a = strptime('22-09-2008', '%d-%m-%Y');
$timestamp = mktime(0, 0, 0, $a['tm_mon']+1, $a['tm_mday'], $a['tm_year']+1900)

还有strptime()，它只需要一种格式:

$a = strptime('22-09-2008', '%d-%m-%Y');
$timestamp = mktime(0, 0, 0, $a['tm_mon']+1, $a['tm_mday'], $a['tm_year']+1900);

警告:

Windows系统不支持该功能 该函数在PHP 8.1.0中已弃用。非常不鼓励依赖这个函数。

使用strtotime()函数，您可以轻松地将日期转换为时间戳

<?php
// set default timezone
date_default_timezone_set('America/Los_Angeles');

//define date and time
$date = date("d M Y H:i:s");

// output
echo strtotime($date);
?> 

更多信息:http://php.net/manual/en/function.strtotime.php

在线转换工具:http://freeonlinetools24.com/

function date_to_stamp( $date, $slash_time = true, $timezone = 'Europe/London', $expression = "#^\d{2}([^\d]*)\d{2}([^\d]*)\d{4}$#is" ) {
    $return = false;
    $_timezone = date_default_timezone_get();
    date_default_timezone_set( $timezone );
    if( preg_match( $expression, $date, $matches ) )
        $return = date( "Y-m-d " . ( $slash_time ? '00:00:00' : "h:i:s" ), strtotime( str_replace( array($matches[1], $matches[2]), '-', $date ) . ' ' . date("h:i:s") ) );
    date_default_timezone_set( $_timezone );
    return $return;
}

// expression may need changing in relation to timezone
echo date_to_stamp('19/03/1986', false) . '<br />';
echo date_to_stamp('19**03**1986', false) . '<br />';
echo date_to_stamp('19.03.1986') . '<br />';
echo date_to_stamp('19.03.1986', false, 'Asia/Aden') . '<br />';
echo date('Y-m-d h:i:s') . '<br />';

//1986-03-19 02:37:30
//1986-03-19 02:37:30
//1986-03-19 00:00:00
//1986-03-19 05:37:30
//2012-02-12 02:37:30

如果已经有了该格式的日期，则只需要在PHP中调用“strtotime”函数。

$date = '22-09-2008';
$timestamp = strtotime($date);
echo $timestamp; // 1222041600

或在单行中:

echo strtotime('22-09-2008');

简短而简单。

对于PHP >=5.3, 7和8，这可能工作-

$date = date_parse_from_format('%Y-%m-%d', "2022-11-15"); //here you can give your desired date in desired format. 
                                                           //just need to keep in mind that date and format matches.

$timestamp = mktime(0, 0, 0, $date['month'], $date['day'], $date['year'] + 2000); //this will return the timestamp

$finalDate= date('Y-m-d H:i:s', $timestamp); //now you can convert your timestamp to desired dateTime format.

文档:

date_parse_from_format () mktime () 日期()