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PHP Global变量定义当前页面的全局变量

Jun 13, 2016 am 11:10 AM
global php but effect overall situation variable definition yes of this

1:PHP Global变量的作用是定义全局变量,但是这个全局变量不是应用于整个网站,而是应用于当前页面,包括include或require的所有文件

  1. $a=123;  
  2.  
  3. function aa()  
  4. {  
  5. Global $a;   
  6. //如果不把$a定义为global变量
    ,函数体内是不能访问$a的  
  7. echo $a;  
  8. }  
  9. aa();  

总结:在函数体内定义的PHP Global变量,函数体外可以使用,在函数体外定义的global变量不能在函数体内使用,

<ol class="dp-xml">
<li class="alt"><span><span>$glpbal $a;  </span></span></li>
<li>
<span>$</span><span class="attribute">a</span><span>=</span><span class="attribute-value">123</span><span>;  </span>
</li>
<li class="alt"><span> </span></li>
<li><span>function f()  </span></li>
<li class="alt"><span>{  </span></li>
<li><span>echo $a; //错误,  </span></li>
<li class="alt"><span>}  </span></li>
</ol>
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再看看下面一例

<ol class="dp-xml">
<li class="alt"><span><span>function f()  </span></span></li>
<li><span>{  </span></li>
<li class="alt"><span>global $a;  </span></li>
<li>
<span>$</span><span class="attribute">a</span><span>=</span><span class="attribute-value">123</span><span>;  </span>
</li>
<li class="alt"><span>}  </span></li>
<li><span> </span></li>
<li class="alt"><span>f();  </span></li>
<li><span>echo $a; //正确,可以使用 </span></li>
</ol>
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2:PHP Global变量问题解析:

question:我在config.inc.php中定义了一些变量($a),在别的文件中函数外部 include("config.inc.php"),函数内部需要使用这些变量$a,如果没有声明的话,echo $a是打印不出来任何东西的。因此声明global $a,但是有很多函数和很多变量,总不能不断重复的这样声明吧?有什么好的解决办法,请指点。

answer1:先在config.inc.php里定义常量:define(常量名,常量值),再在其他需要用到的地方require 'config.inc.php',然后就能在这个文件里直接使用这个常量了。

answer2:我也有个办法,就是定义数组,如$x[a],$x,那样就只要声明global $x一个了。

answer3:我试了你的这个方法,不行啊。

answer4:改你的php.ini文件。

设置PHP Global变量 为 on


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