How would I call a function in another file?

Question

For example, I have a file error-status.php, which includes a function:

function validateHostName($hostName)
{
    if ((strpbrk($hostName,'`~!@#$^&*()=+.[ ]{}\\|;:\'",<>/?')==FALSE) && !ctype_digit($hostName) && eregi("^([a-z0-9-]+)$",$hostName) && ereg("^[^-]",$hostName) && ereg("[^-]$",$hostName))
    {
        return true;
    }
    else
    {
        return false;
    }
}

...

How do I call that function from a different PHP file after invoking require_once?

require_once('error-status.php');

Answer 1

Include the file before you call the function.

include 'error-status.php';
validateHostName('myhostname'); 

Answer 2

I would simply extend the class or use the require /include, then:

$var = new otherClass;
$getString = $var->getString();