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PHP 语法 (Syntax)

Jun 23, 2016 pm 02:35 PM

基本的 PHP 语法 (Syntax)

如果你要在网页里写一段 PHP 代码,你应以 为结束。

<?php?>
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在支持简写的服务器上,你可以使用 来开始和结束 PHP 脚本块。

<??>
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为了保证你的 PHP 文件能够在不同环境下正常运行,强烈建议你使用第一种方法。即以 结束。

一个简单的 PHP 文件的例子

你可以用 Notepad 编写如下代码,这就是一个最简单的 PHP 文件。

<html><body><?php echo "Blabla.cn" ?></body></html>
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其中的 echo 是 PHP 最常用的函数之一,作用是输出文本。

保存 PHP 文件

PHP 文件以 .php 作为文件扩展名。

比如你可以将上面的例子保存为 blabla.php。

运行 PHP 示例文件

在浏览器里输入上述 PHP 示例文件的 URL 路径,你会看到显示的结果是:

Blabla.cn
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请用浏览器查看该示例网页源代码,你会发现,你看不到上面示例文件中写的 PHP 代码,你看到的只是 PHP 脚本执行后形成的 HTML ,如下所示:

<html><body>Blabla.cn</body></html>
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用户看不到 PHP 文件的源代码,只能看到 PHP 文件执行后的输出结果。

PHP 语言中分号 (Semicolon) 的作用: 指令分隔符 (Instruction separation)

PHP 语言中,分号 (Semicolon) 表示一个 PHP 指令的结束,记住在每个 PHP 指令结束后加上分号,不过在一个 PHP 脚本块中,最后一个指令后可以不必加分号,因为 ?> 自动暗含了一个分号,当然你加分号也不会出错。

比如我们用分号分隔两个 echo 语句,如下:

<html><body><?phpecho "Blabla.cn";echo "Hello"?></body></html>
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空格

空格在两个 PHP 指令之间是被忽略的。

下面三种写法,输出 HTML 结果是一样的。

<?phpecho "Blabla.cn";echo "Hello"?>
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<?phpecho "Blabla.cn";echo "Hello"?>
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<?phpecho "Blabla.cn";echo "Hello"?>
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