PHP基本语法的小结，PHP基本语法小结
PHP基本语法的小结，PHP基本语法小结
一、PHP能做什么？
PHP能做什么？我觉得它很强大，只要我能想到的，它都能做，只是我技术能力还不行╮(╯﹏╰）╭。好吧，一张图，基本了解一下吧（ps:PHP的功能不局限于此( ^_^ )）
图像有点模糊，凑合一下，(≧▽≦)/
二、PHP语言标记
1、结束和开始标记
1.1 :属于xml风格，是PHP的标准风格，推荐使用。
1.2 :长风格标记，不常用。若你的奇葩编辑器不支持其他php标记，就用它吧
1.3 //code ?>:简短风格，遵循SGML处理。需要在php.ini中将指令short_open_tag打开，或者在php编译时加入–enable- short-tags.如果你想你的程序移植性好，就抛弃这种风格，它就比1.1少了个php。
2、位置
怎么说呢？反正可以将PHP语言放在后缀名为.php的HTML文件的任何地方。注意了，是以.php结尾的HTML文件。
<span id="lnum1"> 1:<span> <html></span></span>
<span id="lnum2"> 2:<span> <head></span></span>
<span id="lnum3"> 3:<span> <meta http-equiv=<span>"content-type" content=<span>"text/html;charset=utf-8"></span></span></span></span>
<span id="lnum4"> 4:<span> <!-- 在HTML标记中嵌入脚本 --></span></span>
<span id="lnum5"> 5:<span> <title><?php <span>echo <span>"PHP语言标记" ?></title></span></span></span></span>
<span id="lnum6"> 6:<span> </head></span></span>
<span id="lnum7"> 7:<span> <!-- 在属性位置嵌入 --></span></span>
<span id="lnum8"> 8:<span> <body <?php <span>echo <span>'bgcolor="#ccc"'?>></span></span></span></span>
<span id="lnum9"> 9:<span> <!-- 来个高级点的吧 --></span></span>
<span id="lnum10"> 10:<span> <?php</span></span>
<span id="lnum11"> 11:<span> <span>if($exp){</span></span></span><span id="lnum12"> 12:<span> ?></span></span>
<span id="lnum13"> 13:<span> <!-- 属性值中嵌入php --></span></span>
<span id="lnum14"> 14:<span> <p align=<span>"<?php echo 'center'?>">条件为true该做的</p></span></span></span>
<span id="lnum15"> 15:<span> <?php</span></span>
<span id="lnum16"> 16:<span> }<span>else{</span></span></span><span id="lnum17"> 17:<span> ?></span></span>
<span id="lnum18"> 18:<span> <p>条件为FALSE该做的</p></span></span>
<span id="lnum19"> 19:<span> <?php</span></span>
<span id="lnum20"> 20:<span> }</span></span>
<span id="lnum21"> 21:<span> ?></span></span>
<span id="lnum22"> 22:<span> </body></span></span>
<span id="lnum23"> 23:<span> </html></span></span>
3、注释
3.1 单行注释：// 或者 # 多行注释：/* 说明*/
3.2 多行注释不能嵌套，但是其中可以包含单行注释；单行注释也可以包含多行注释。就想这样子
<span id="lnum1"> 1:<span> <?php</span></span>
<span id="lnum2"> 2:<span> <span>//echo "test";/*单行中包含多行注释符*/</span></span></span>
<span id="lnum3"> 3:<span> <span>/*echo 'test'; //多行注释符中包含单行注释符*/</span></span></span>
<span id="lnum4"> 4:<span> ?></span></span>
三、变量
1、变量的使用
<span id="lnum1"> 1:<span> <?php</span></span>
<span id="lnum2"> 2:<span> $a = 1; <span>//声明一个变量a</span></span></span>
<span id="lnum3"> 3:<span> $b = <span>"php"; <span>//声明一个变量b</span></span></span></span>
<span id="lnum4"> 4:<span> $8d = 2; <span>//非法变量名，只能以字母或者下划线开头且不包含空格</span></span></span>
<span id="lnum5"> 5:</span>
<span id="lnum6"> 6:<span> $i站点is = <span>"php"; <span>//合法变量名，可以使用中文</span></span></span></span>
<span id="lnum7"> 7:<span> <span>/*</span></span></span>
<span id="lnum8"> 8:<span> <span> *以下三个函数调用方式等效</span></span></span>
<span id="lnum9"> 9:<span> <span> *关键字和内置函数及用户自定义的类名，函数名不区分大小写</span></span></span>
<span id="lnum10"> 10:<span> <span> */</span></span></span>
<span id="lnum11"> 11:<span> phpinfo();</span></span>
<span id="lnum12"> 12:<span> PhpInfo();</span></span>
<span id="lnum13"> 13:<span> PHPINFO();</span></span>
<span id="lnum14"> 14:</span>
<span id="lnum15"> 15:</span>
<span id="lnum16"> 16:<span> <span>/*</span></span></span>
<span id="lnum17"> 17:<span> <span> *以下三个变量不一样</span></span></span>
<span id="lnum18"> 18:<span> <span> *变量名是区分大小写滴</span></span></span>
<span id="lnum19"> 19:<span> <span> */</span></span></span>
<span id="lnum20"> 20:<span> $name = <span>"php1";</span></span></span>
<span id="lnum21"> 21:<span> $Name = <span>"php2";</span></span></span>
<span id="lnum22"> 22:<span> $NAME = <span>"php3";</span></span></span>
<span id="lnum23"> 23:</span>
<span id="lnum24"> 24:<span> <span>//可变变量：变量名可以动态的设置</span></span></span>
<span id="lnum25"> 25:<span> $hi = <span>"hello";</span></span></span>
<span id="lnum26"> 26:<span> $$hi = <span>"world";</span></span></span>
<span id="lnum27"> 27:<span> <span>//以下均输出hello world</span></span></span>
<span id="lnum28"> 28:<span> <span>echo <span>"$hi $hello";</span></span></span></span>
<span id="lnum29"> 29:<span> <span>echo <span>"$hi ${$hi}";</span></span></span></span><span id="lnum30"> 30:</span>
<span id="lnum31"> 31:<span> <span>//变量赋值</span></span></span>
<span id="lnum32"> 32:<span> $foo = <span>"B" <span>//传值赋值</span></span></span></span>
<span id="lnum33"> 33:<span> $bar = &$foo <span>//引用赋值</span></span></span>
<span id="lnum34"> 34:<span> $bar = <span>"LZ";</span></span></span>
<span id="lnum35"> 35:<span> <span>echo <span>"$foo"; <span>//输出LZ</span></span></span></span></span>
<span id="lnum36"> 36:<span> $cde = $foo; <span>//传值赋值</span></span></span>
<span id="lnum37"> 37:<span> $cde = <span>"E";</span></span></span>
<span id="lnum38"> 38:<span> <span>echo <span>"$foo"; <span>//输出LZ</span></span></span></span></span>
<span id="lnum39"> 39:<span> ?></span></span>
2、变量的类型
四、常量
1、定义和使用
<span id="lnum1"> 1:<span> <?php</span></span>
<span id="lnum2"> 2:<span> <span>/*</span></span></span>
<span id="lnum3"> 3:<span> <span> *boolean define(string name,mixed value[,bool case_insensitive)</span></span></span>
<span id="lnum4"> 4:<span> <span> *name:常量名；value:常量值；第三个是个可选的布尔值，默认是FALSE（不区分大小写）</span></span></span>
<span id="lnum5"> 5:<span> <span> */</span></span></span>
<span id="lnum6"> 6:<span> define(<span>"FLO",1000);</span></span></span>
<span id="lnum7"> 7:<span> <span>echo FLO; <span>//输出1000</span></span></span></span>
<span id="lnum8"> 8:</span>
<span id="lnum9"> 9:<span> <span>//使用define函数检验FLO常量是否存在，存在则输出常量值</span></span></span>
<span id="lnum10"> 10:<span> <span>if(define(<span>"FLO"))</span></span></span></span>
<span id="lnum11"> 11:<span> {</span></span><span id="lnum12"> 12:<span> <span>echo FLO;</span></span></span>
<span id="lnum13"> 13:<span> }</span></span>
<span id="lnum14"> 14:<span> ?></span></span>
2、常量和变量
2.1 常量的作用域是全局的，可以再脚本的任何地方声明和访问常量。
2.2 常量前面没有$,且不能通过赋值语句定义常量。
2.3 常量一旦被定义，不能被重新定义或取消定义，直到脚本运行结束自动释放。
2.4 常量的值只能是标量（boolean，integer,float,string中的一种类型)
3、系统的预定义常量
4、常用的魔术常量
来源：http://www.ido321.com/510.html
双引号是用于输出字符串的。例如：echo "数据插入失败，错误信息：
";
而"INSERT INTO testtable VALUES('".$xm."',".$nl.")"; 中INSERT INTO testtable VALUES是字符串，意思是向数据库中插入，两个""是一组，将.$xm.分开，(.$xm.)中$xm是一个变量，php中显示一个变量时用echo。
《PHP和MySQL Web开发》这本”php圣经“，比较起来，《零基础学PHP》比较符合初学者，看这本书很容易感受到作者是用心写的。
这本书其实是《零基础学编程》系列其中的一本，其他的都很不错。
内容的设计很好。有一段前言，写的非常中肯，是程序员老鸟给菜鸟的忠告，摘录在此：
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
学习编程需要注意的几点：
1.不要死记语法﹕很多初学者试图把各种语法背下来﹐其实这是极其错误的﹐程序开发的语法﹑规范特别多﹐ 不可能都记得下来﹐你只要知道有这么一个功能就可以了﹐需要的时候翻阅书籍﹐或者查找帮助文件﹐这样省时省力。
2.多手﹐多练习﹕只知道死啃书本的人﹐是不会成为开发高手的﹐只有多上机编写程序﹐才能在实践中提高对编程的认识。
3.遇到问题﹐首先尝试自己解决﹕自己先用一在的时间﹐尽力去解决﹐实在不行再去找人帮助﹐千万不要遇到问题立刻找人帮忙﹐ 这样永远提高不了多少。
4.多用Google,Baidu:网络是一个大知识库﹐是最好的老师﹐你遇到的问题﹐别人也遇到过﹐多去搜索一下吧。
4.多阅读别人的源代码﹕要看懂别人的设计思想﹐不断融为已用。
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
本书的缺点是代码前面没有行标，而在对代码的解释中大量使用“在xxx行，”，一个较大的失误。
总结：在知识点方面，《零基础学PHP》可能是不全的，但是，我们需要的不是一本字典，我们需要的一本循循善诱的书，学得有兴趣，不是吗？
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