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浅谈php中include文件变量作用域_PHP

May 30, 2016 am 08:44 AM
php

在php中我们有时候需要include一个文件。比如我前段时间在写一个框架的时候,打算用原生的php作为模板,然后写一个display方法引入模板文件就可以,但是这只是我的意淫而已。

写完后发现在模板中所有的变量都提示未定义。通过各种研究和查找资料,总结了include文件时的几种情况下的作用域。

第一种情况:A文件include B文件,在B文件中可以调用A中的变量。

A文件代码:

<&#63;php
 $aaa = '123';
 
 include "B.php";
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B文件代码:

<&#63;php

echo $aaa;

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可以正常输出内容。

第二种情况:A文件include B文件,然后在A文件中可以调用B文件的变量。
A文件代码:

<&#63;php

include "B.php";

echo $fff;

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B文件代码:

<&#63;php

$fff = 'i am f';

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这个时候是可以正常输出内容的。

第三种情况:A文件的某个类的某个方法中调用B文件,然后在B文件中可以调用该方法中的变量。
A文件代码:

<&#63;php

class test{
  public function show(){
    $bbb = 'abc';
    include "B.php";
  }
}

$t = new test;
$t->show();

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B文件的代码:

<&#63;php

echo $bbb;

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这个时候是可以正常输出内容的。

第四种情况:A文件通过定义的一个函数引入B文件,在B文件中无法使用A中的变量,但是可以使用A文件中调用函数(display)中的变量。
A文件代码:

<&#63;php
$aaa = '123';

function display($file){
  $bbb= 'asdasdas';
  include $file;
}

display("B.php");

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B文件代码:

<&#63;php
echo $aaa;
echo $bbb;
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运行后$aaa提示未定义,$bbb可以正常输出。

所以我开始准本用一个display方法来引入模板是不可行的。根据方面的三种情况,最后我选择了写一个类来导入模板文件。目前ThinkPHP和Smarty也都是用类来引入模板文件的。文中不足之处欢迎指正。

以上所述就是本文的全部内容了,希望大家能够喜欢。

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