PHP - MYSQL fatal error : Constant expression contains invalid operations

Question

这个问题在这里已经有了答案:





PHP Error : Fatal error: Constant expression contains invalid operations

(5 个回答)


2年前关闭。




尝试加载我的网站时，我的 php 脚本出现 fatal error ，代码如下:

<?php

class PDO_DB {

    public $dbh; 
    private static $dsn1  = 'mysql:host='+$_ENV['DB_HOST'];
    private static $dsn2  = ';port=3306;dbname='+$_ENV['DB_NAME'];
    private static $user = $_ENV['DB_USER']; 
    private static $pass = $_ENV['DB_PASS']; 
    private static $dbOptions = array(
        //PDO::ATTR_PERSISTENT => true,
        PDO::ATTR_CASE => PDO::CASE_LOWER,
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION //TODO: remove this line on production (maybe not, just hide php errors, so I can see logs)
    );

    public static function factory() { 

        //$sock = '/var/run/mysql/mysql.sock'; //localhost
        // $sock = '/var/lib/mysql/mysql.sock';

        if(!isset(self::$dbh)){
            $dbh = new PDO(self::$dsn1.self::$dsn2,self::$user,self::$pass, self::$dbOptions); 
        }
        return $dbh;
    }

}

?>

它告诉我 fatal error :常量表达式在第 6 行的 D:\Servers\wamp64\www\classes\PDO.class.php 中包含无效操作

谁能帮我 ？

Answer 1

替换这个-> private static $dsn1 = 'mysql:host='+$_ENV['DB_HOST']; , 用这个 -> private static $dsn1 = 'mysql:host='.$_ENV['DB_HOST'];
您不能使用 +组合字符串和变量，如 JavaScript ，您必须使用 .