81 lines
1.3 KiB
Markdown
81 lines
1.3 KiB
Markdown
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---
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title: PHP Syntax
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localeTitle: PHP语法
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---
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# 基本的PHP语法
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### 开始
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所有PHP文件都以`.php`扩展名保存。 PHP脚本可以添加到文档中的任何位置。 PHP脚本以`<?php`开头，以`?>`结尾。
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`<?php //PHP code goes here ?>`
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### 打印
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要在PHP中打印任何语句，我们使用`echo`命令。
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#### 代码示例
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```
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<!DOCTYPE html>
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<html>
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<body>
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<h1>My first PHP page</h1>
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<?php
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echo "Hello World!";
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?>
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</body>
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</html>
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```
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##### 注意：PHP语句以分号结尾`;`
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### 声明变量
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我们通过在它们之前添加美元`$`符号在PHP中声明变量。
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```
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<?php
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$x = 5;
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echo $x;
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?>
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```
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### PHP中的评论
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要在PHP中编写单行注释，我们将hashtag `#`或在注释之前放置`//` 。
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```
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<?php
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# This is a single line comment
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// This is also a single line comment
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?>
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```
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要写双行注释，我们用`/*`开始注释，用`*/`结束。
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```
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<?php
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/* This is a
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Double line comment. */
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?>
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```
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我们还可以注释掉代码行的某些部分。
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#### 代码示例
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```
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<!DOCTYPE html>
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<html>
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<body>
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<?php
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// You can also use comments to leave out parts of a code line
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$x = 5 /* + 15 */ + 5;
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echo $x;
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?>
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</body>
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</html>
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```
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您可以在[PHP手册](http://php.net/manual/en/)上看到更多相关信息
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