PHP redirect to a domain if the called domain is equal to another domain

Question: Is it possible to redirect a user opening a domain to a different domain through the use of PHP?
Say the user goes to www.domainA.com and I want to redirect them to www.domainB.com, how would I do so without the use of a meta refresh? Possible?
Answer:
$host = $_SERVER['HTTP_HOST'];$hosts = array(
'roganmedical.com' ,
'roganmedical.com' ,
'www.roganmedical.com' , 'http://roganmedical.com' , 'http://www.roganmedical.com' , 'rogan-medical.ch' , 'www.rogan-medical.ch' , 'http://rogan-medical.ch' , 'http://www.rogan-medical.ch' , 'schmerzen-wastun.ch' , 'www.schmerzen-wastun.ch' , 'http://schmerzen-wastun.ch' , 'http://www.schmerzen-wastun.ch' );if(in_array($host, $hosts)) { header('Location: http://www.roganmedical.ch');}