프론트엔드에서 PHP의 기본 구문을 알아보세요.

<?<span>php
  </span><span>//
</span>?>

<?<span>php
    echo </span><span>"</span><span>Hello World!</span><span>"</span><span>;
</span>?>

<?<span>php
</span><span>//</span><span> 这是单行注释</span><span>#这也是单行注释

</span><span>/*</span><span>这是多行注释块
它横跨多行
</span><span>*/</span>?>

<?<span>php
    echo </span><span>"</span><span><h2>PHP is fun!</h2><span>"</span><span>;
    echo </span><span>"</span><span>Hello world!<br></span><span>"</span><span>;
    echo </span><span>"</span><span>I'm about to learn PHP!<br></span><span>"</span><span>;
    echo </span><span>"</span><span>This</span><span>"</span>, <span>"</span><span> string</span><span>"</span>, <span>"</span><span> was</span><span>"</span>, <span>"</span><span> made</span><span>"</span>, <span>"</span><span> with multiple parameters.</span><span>"</span><span>;
</span>?>

<?<span>php
    print </span><span>"</span><span><h2>PHP is fun!</h2><span>"</span><span>;
    print </span><span>"</span><span>Hello world!<br></span><span>"</span><span>;
    print </span><span>"</span><span>I'm about to learn PHP!<br></span><span>"</span><span>;
    </span><span>//</span><span>该行出错，因为print只能输出1个字符串</span>    print <span>"</span><span>This</span><span>"</span>, <span>"</span><span> string</span><span>"</span>, <span>"</span><span> was</span><span>"</span>, <span>"</span><span> made</span><span>"</span>, <span>"</span><span> with multiple parameters.</span><span>"</span><span>;
</span>?>

<?<span>php
    </span><span>//</span><span>36</span>    echo <span>12</span>*<span>3</span><span>;
</span>?>

<?<span>php
    </span><span>//</span><span>Hello World!</span>    ECHO <span>"</span><span>Hello World!<br></span><span>"</span><span>;
    </span><span>//</span><span>Hello World!</span>    echo <span>"</span><span>Hello World!<br></span><span>"</span><span>;
    </span><span>//</span><span>Hello World!</span>    EcHo <span>"</span><span>Hello World!<br></span><span>"</span><span>;
</span>?>

<?<span>php
    $color</span>=<span>"</span><span>red</span><span>"</span><span>;
    </span><span>//</span><span>My car is red</span>    echo <span>"</span><span>My car is </span><span>"</span> . $color . <span>"</span><span><br></span><span>"</span><span>;
    </span><span>//</span><span>My house is </span>    echo <span>"</span><span>My house is </span><span>"</span> . $COLOR . <span>"</span><span><br></span><span>"</span><span>;
    </span><span>//</span><span>My boat is</span>    echo <span>"</span><span>My boat is </span><span>"</span> . $coLOR . <span>"</span><span><br></span><span>"</span><span>;
</span>?>