print date('Y');

有关更多信息，请查看date()函数文档:https://secure.php.net/manual/en/function.date.php

顺便说一句……网站版权展示有几种合适的方式。有些人倾向于让事情变得多余，例如:版权©具有相同的含义。重要的版权部分包括:

**Symbol, Year, Author/Owner and Rights statement.** 

使用PHP + HTML:

<p id='copyright'>&copy; <?php echo date("Y"); ?> Company Name All Rights Reserved</p>

or

<p id='copyright'>&copy; <?php echo "2010-".date("Y"); ?> Company Name All Rights Reserved</p

全年使用:

 <?php 
    echo $curr_year = date('Y'); // it will display full year ex. 2017
?>

或者只得到两位年份，就像这样:

 <?php 
    echo $curr_year = date('y'); // it will display short 2 digit year ex. 17
?>

我是这么做的:

<?php echo date("d-m-Y") ?>

下面是对它功能的一些解释:

d = day
m = month
Y = year

Y表示四位数(如1990)，Y表示两位数(如90)

我显示版权的方式，它会自动更新

<p class="text-muted credit">Copyright &copy;
    <?php
        $copyYear = 2017; // Set your website start date
        $curYear = date('Y'); // Keeps the second year updated
        echo $copyYear . (($copyYear != $curYear) ? '-' . $curYear : '');
    ?> 
</p>    

它将输出结果为

copyright @ 2017   //if $copyYear is 2017 
copyright @ 2017-201x    //if $copyYear is not equal to Current Year.

在date函数的第二个参数中可以得到更多的值 Strtotime返回参数传递的时间戳

// This work when you get time as string
echo date('Y', strtotime("now"));

// Get next years
echo date('Y', strtotime("+1 years"));

// 
echo strftime("%Y", strtotime("now"));

使用datetime类

echo (new DateTime)->format('Y');