PHP大小写是否敏感问题 - zzwind's Blog

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PHP大小写是否敏感问题

zzwind posted @ 2010年7月16日 18:09 in php , 2471 阅读

一、大小写敏感

1. 变量名区分大小写

所有变量均区分大小写，包括普通变量以及$_GET,$_POST,$_REQUEST,$_COOKIE,$_SESSION,$GLOBALS,$_SERVER,$_FILES,$_ENV等；

    
            1
            <?php
        
            2
            $abc = 'abcd';
        
            3
            echo $abc; //输出 'abcd'
        
            4
            echo $aBc; //无输出
        
            5
            echo $ABC; //无输出

2. 常量名默认区分大小写，通常都写为大写

（但没找到能改变这个默认的配置项，求解）

    
            1
            <?php
        
            2
            define("ABC","Hello World");
        
            3
            echo ABC;   //输出 Hello World
        
            4
            echo abc;   //输出 abc

3. php.ini配置项指令区分大小写

如 file_uploads = 1 不能写成 File_uploads = 1

二、大小写不敏感

1. 函数名、方法名、类名不区分大小写，但推荐使用与定义时相同的名字

    
            1
            <?php
        
            2
            function show(){
        
            3
            echo "Hello World";
        
            4
            }
        
            5
            show(); //输出 Hello World    推荐写法
        
            6
            SHOW(); //输出 Hello World

    
            1
            <?php
        
            2
            class cls{
        
            3
            static function func(){
        
            4
            echo "hello world";
        
            5
            }
        
            6
            }
        
            7
             
            8
            Cls::FunC();  //输出hello world

2. 魔术常量不区分大小写，推荐大写

包括：__LINE__、__FILE__、__DIR__、__FUNCTION__、__CLASS__、__METHOD__、__NAMESPACE__。

    
            1
            <?php
        
            2
            echo __line__;  //输出 2
        
            3
            echo __LINE__;  //输出 3

3. NULL、TRUE、FALSE不区分大小写

    
            01
            <?php
        
            02
            $a = null;
        
            03
            $b = NULL;
        
            04
             
            05
            $c = true;
        
            06
            $d = TRUE;
        
            07
             
            08
            $e = false;
        
            09
            $f = FALSE;
        
            10
             
            11
            var_dump($a == $b); //输出 boolean true
        
            12
            var_dump($c == $d); //输出 boolean true
        
            13
            var_dump($e == $f); //输出 boolean true

4.类型强制转换，不区分大小写

包括

(int)，(integer) – 转换成整型
(bool)，(boolean) – 转换成布尔型
(float)，(double)，(real) – 转换成浮点型
(string) – 转换成字符串
(array) – 转换成数组
(object) – 转换成对象

    
            1
            <?php
        
            2
            $a=1;
        
            3
            var_dump($a);  //输出 int 1
        
            4
             
            5
            $b=(STRING)$a;
        
            6
            var_dump($b);  //输出string '1' (length=1)
        
            7
             
            8
            $c=(string)$a;
        
            9
            var_dump($c);  //输出string '1' (length=1)

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zzwind's Blog

PHP大小写是否敏感问题 - zzwind's Blog

PHP大小写是否敏感问题

一、大小写敏感

1. 变量名区分大小写

2. 常量名默认区分大小写，通常都写为大写

3. php.ini配置项指令区分大小写

二、大小写不敏感

1. 函数名、方法名、类名 不区分大小写，但推荐使用与定义时相同的名字

2. 魔术常量不区分大小写，推荐大写

3. NULL、TRUE、FALSE不区分大小写

4.类型强制转换，不区分大小写

1. 函数名、方法名、类名不区分大小写，但推荐使用与定义时相同的名字