CODEWITHSUNDEEP
phpmysqldatabase-connection
user3361761
user3361761

Reputation: 259

Trouble with using globally defined variables: 'Use of undefined constant'

I have this code:

<?php

$db_initiallized = false;
$db_connection = NULL;

function db_init()
{
    global $db_initiallized, $db_connection;

    if(!$db_initiallized) //error occurs on this line
    {
        $db_connection = mysql_connect("server", "username", "password");
        if(!$db_connection)
        {
            echo 'Connection failure!';
            exit();
        }

        $db_initiallized = true;
    }
}

?>

And I get the error:

Use of undefined constant

I'm not sure why this error is occurring. Perhaps I am declaring global variables wrong. What's going on here?

Upvotes: 0

Views: 826

Answers (1)

Lucas Henrique
Lucas Henrique

Reputation: 1364

The $GLOBALS array can be used instead:

$GLOBALS['db_initiallized'] = false;
$GLOBALS['db_connection'] = NULL;

function db_init(){

    echo $GLOBALS['db_initiallized'];
    echo $GLOBALS['db_connection'];
}

OR

If the variable is not going to change you could use define.

define('db_initiallized', FALSE);
define('db_connection', NULL);

function db_init()
{
    echo db_initiallized;
    echo db_connection;
}

OR

If you have a set of functions that need some common variables, a class with properties may be a good choice instead of a global:

class MyTest
{
    protected $a;

    public function __construct($a)
    {
        $this->a = $a;
    }

    public function head()
    {
        echo $this->a;
    }

    public function footer()
    {
        echo $this->a;
    }
}

$a = 'localhost';
$obj = new MyTest($a);

Upvotes: 1

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