template in message string

hi guys i am trying to setup predefined messages which will contain variables than need to go through it for instance Hello {username} you have changed your pass to {pass} this is the message setup in my settings,ini file which i extract using parse_ini_file , i basically need to find a way to convert both ther {username} and {pass} and send the variables of the same name to the string for instance $username = "dan" $pass = "dan" Hello {username} you have changed your pass to {pass} any ideas ?