为什么两次调用相同的函数会导致php致命错误？

Question

https://plnkr.co/edit/ZNlAyky7TzT4jknpnoDJ?p=preview

here is a link to a plnkr with all my code written so far. I keep getting an

Fatal error: Cannot redeclare connect_to_db() (previously declared in /var/www/html/News/config/dbconnect.php:5) in /var/www/html/News/config/dbconnect.php on line 5

the plunkr wont have the folder structure because i could not figure out how to add folders however here is my code for dbconnect.php

 <?php
        $pdo = null;
        function connect_to_db()
        {
            $dbengine   = 'mysql';
            $dbhost     = 'localhost';
            $dbuser     = 'root';
            $dbpassword = 'password';
            $dbname     = 'news';

            try{
                $pdo = new PDO("".$dbengine.":host=$dbhost; dbname=$dbname", $dbuser,$dbpassword);
                $pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_OBJ);
                return $pdo;
            }
            catch (PDOException $e){
                $e->getMessage();
            }
        }

line 5 does not have a call to db connect so i dont know what is going on

Answer 1

You are using

require __DIR__.'/dbconnect.php'

In both your Index.php and your functions.php, while requiring your functions.php in Index.php.

Therefore connect_to_db() is being defined twice. Use require_once instead to prevent this:

require_once __DIR__.'/dbconnect.php'

http://php.net/manual/en/function.require-once.php