第四章_PHP基本语法_PHP教程

1.第一个PHP程序

<span> <span><span>
<span> <?<span php><span>     <span echo> "<span hello php><span> ?></span></span></span></span></span></span></span></span></span>

2.PHP共支持8种基本数据理性，包括4种标量类型：boolean（布尔型）、integer（整型）、float（浮点型，也称为double）、string（字符串），2种复合类型：array（数组）、object（对象），2种特殊类型：resource（资源）、NULL（空类型）

3.函数var_dump可以用来打印变量的相关信息。

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<span> <?<span php><span>     <span var_dump>((bool) <span false><span><span>     <span var_dump>((bool) 0<span><span>     <span var_dump>((bool) 0.0<span><span>     <span var_dump>((bool) ''<span><span>     <span var_dump>((bool) "0"<span><span>     <span var_dump>((bool) <span array><span><span>     <span var_dump>((bool) <span null><span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

4.关于整型。

　　在32位操作系统中，整型数的有效范围是-2147483648~+2147483647。如果超过了这个范围，将会被PHP引擎解释成浮点数（float）。

　　用八进制加0，用十六进制加0x（是数字0而非字母O）

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<span> <?<span php><span>     <span>=63<span><span>     <span var_dump>(<span><span><span>     
<span>     <span>=077<span><span>     <span var_dump>(<span><span><span>     
<span>     <span>=0x3f<span><span>     <span var_dump>(<span><span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

5.字符串型

　　有3种定义字符串的方式，分别是单引号（‘）、双引号（“）和界定符（

<span> <?<span php><span>     <span>='麦兜'<span><span>     <span>=19<span><span>     <span echo> '本人大名$name，年方$age'<span><span>     <span echo> '<p>'<span><span>     <span echo> "本人大名<span>,年方<span>"<span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

　　关于界定符使用如下：

<span> <?<span php><span>     <span echo> <<<<span my_str><span> <span><span> <span my_str><span> ?></span></span></span></span></span></span></span></span></span></span>

 6.对象类型

<span> <?<span php><span> <span class><span person><span>     <span public> <span><span><span>     <span private> <span><span><span>     
<span>     <span function> Person(<span>,<span><span><span>         <span>->name=<span><span><span>         <span>->age=<span><span><span> <span><span>     
<span>     <span function><span getinfo><span>         <span echo> '我叫'.<span>->name.'<br>我今年'.<span>->age.'岁了'<span><span> <span><span> <span><span>     <span> = <span new> Person("kimi",5<span><span>     <span>-><span getinfo><span> ?>    </span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

7.类型转换

　　print_r() 显示关于一个变量的易于理解的信息。如果给出的是 string、integer 或 float，将打印变量值本身。如果给出的是 array，将会按照一定格式显示键和元素

<span> <?<span php><span>     <span>=3.141592653<span><span>     <span>=(<span string>)<span><span><span>     <span echo> "<p><span>"<span><span>     
<span>     <span>='Kimi'<span><span>     <span>=(<span array>)<span><span><span>     <span echo> '<p>'<span><span>     <span print_r>(<span><span><span>     
<span>     <span>='Cindy'<span><span>     <span>=(<span unset>)<span><span><span>     <span echo> '<p>'<span><span>     <span var_dump>(<span><span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>