Front-end PHP entry -013-variable scope

At the moment, we know a few different rules:

• When a function is defined, the variable that is enclosed in parentheses is a formal parameter (formal parameter), which has no relation to a variable outside the body of the function. It's just inside the function.
• Variables declared within a function are also irrelevant to variables outside the function.

However, we will encounter such a situation in the actual processing situation:

• I want to define variables in the function body for external use
• I want to get the variables outside the function body to use in the body.

1. Read external variables via $globlas

  

   
<?php
   

   
    $one = 10;
   

   
    function demo(){
   
        $two = 100;
   

   
        $result = $two + $GLOBALS[‘one‘];
   

   
        return $result;
   

   
    }
   
    //你会发现结果变成了110
   
    echo demo();
   

   
?>
  

in the example above : we get the function body to use the variable outside the function body through $globals. Therefore, a variable outside the function cannot be used within the function body.

2. Modify the external variables within the function by $globlas

  

   
<?php
   

   
    $pangsir = ‘我是一个兵，来自老百姓‘;
   

   
    function test(){
   

   
        echo ‘执行了函数test哟<br />‘;
   
        //调用test()函数，将通过$GLOBALS[‘pangsir‘],把$pangsir 的值改变掉
   

   
        $GLOBALS[‘pangsir‘] = ‘帮助别人很快乐‘;
   
    }
   

   
    test();
   
    //发现是不是输出的值变了呀？
   
    echo $pangsir;
   

   
?>
  

By the example above: we found that through GLOBALS [ PaNg sI R- ],put G l O B A L S [ p a n G s i r ] , put The value of the Pangsir is changed, so the value changes when the last output $pangsir.

3. Create a global variable within a function by $globlas

  

   
<?php
   

   
    function hello(){
   
        $GLOBALS[‘que‘] = ‘提神喝茶更好哟‘;
   
        echo ‘你调了一下函数hello<br />‘;
   
    }
   

   
    hello();
   

   
    echo $que;
   

   
?>
  

From for notes (Wiz)

Front-end PHP entry -013-variable scope