What is a variable function in PHP? How to use variable functions? (share)

The previous article introduced to you "What is passing parameters by reference? How to use parameter passing by reference? Assignment of reference parameters? (Attached code) 》, this article continues to introduce to you what is a variable function in PHP? How to use variable functions? (Share), let’s learn together! ! !

What is a variable function:

When the value of a variable function is the name string of a certain function, we can Use the variable name () to call the function of the corresponding name. This calling method is the variable function

For example:

$var = 'demo';
function demo(){
         php代码 
}

Usage of variable function: $var() ; Equivalent to demo();

Let’s take the code as an example:

<?php
     /****** 变量函数*/
     $yyds = &#39;study&#39;;
     $study = &#39;努力学习&#39;;
     echo $$yyds;
?>

Before learning the variable function, let’s review the variable variables we talked about before. First, let’s first Assign an initial value to $yyds as study, and then assign 'study hard' to study; when we output (echo) $$yyds, the result we output will be the word study hard, ($yyds will be parsed as study, and then continue to parse it into hard study); the running results are as follows:

The above are the variable variables we mentioned;

About Variable function

<?php 
      /****** 变量函数*/
      $yyds = &#39;study&#39;;
      $study = &#39;努力学习&#39;;
      echo $$yyds;
      echo &#39;<hr>&#39;;
      
  
      function textarea($rows=10, $cols=50, $name=&#39;biezhu&#39;,$place=&#39;请您输入内容&#39;){
      echo &#39;<textarea rows="&#39;.$rows.&#39;" cols="&#39;.$cols.&#39;"name= "&#39;.$name.&#39;" placeholder="&#39;.$place.&#39;"></textarea>&#39;;
      }
      textarea();
   
?>

Code analysis:

We still create a function function and define an initial value textarea() (multi-line text input). Then, we directly output (echo) a textarea, When we define multi-line text output, there will also be how many rows, how many columns (row represents rows; cols represents columns), and the default display (placeholder). The content defined above is likely to change, so we Put them in textarea(). When we call textarea(), we run the results and find that we can output the results we entered. The results are as follows:

Variable function

<?php 
      /****** 变量函数*/
      $yyds = &#39;study&#39;;
      $study = &#39;努力学习&#39;;
      echo $$yyds;
      echo &#39;<hr>&#39;;
      
      
      function textarea($rows=10, $cols=50, $name=&#39;biezhu&#39;,$place=&#39;请您输入内容&#39;){
      echo &#39;<textarea rows="&#39;.$rows.&#39;" cols="&#39;.$cols.&#39;"name= "&#39;.$name.&#39;" placeholder="&#39;.$place.&#39;"></textarea>&#39;;
      }
      
  
      //textarea();
      //定义一个变量
      $func = &#39;textarea&#39;;
      //函数变量
      $func();
   
?>

First define a variable as $func='textarea'. At this time, textarea is a string type variable. Then, we add () to the $func variable just defined. , after running the code, I found that it can still be run, and the running results are as follows:

The above is our variable function;

Recommended learning: " PHP video tutorial》

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