php function_exists function problem, repeatedly defining functions

WBOY
Release: 2016-08-04 09:21:29
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<code>$a=get(1);  //出错,找不到定义
echo $a;
if(!function_exists("get")){
   function get($a){
      return "test";
   }
}</code>
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If you want to realize the function, you need to check whether the function is defined. If it is, it will not be defined. If not, just define it.
The function_exists position is at the end of the file, and it will prompt that the function definition cannot be found

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<code>$a=get(1);  //出错,找不到定义
echo $a;
if(!function_exists("get")){
   function get($a){
      return "test";
   }
}</code>
Copy after login
Copy after login

If you want to realize the function, you need to check whether the function is defined. If it is, it will not be defined. If not, just define it.
The function_exists position is at the end of the file, and it will prompt that the function definition cannot be found

<code class="php">if(!function_exists("get")){
   function get($a){
      return "test";
   }
}
$a=get(1); // 这不就找到了
echo $a;</code>
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Recommended methodis_callable, manual

Explanation of sequential execution..

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