How to refresh the result of getservbyname() function?

Question

I configured the following in my /etc/services/ file:

tt16       9898/tcp

and then called the getservbyname() and got port number as 9898 (after ntohs()).

I then changed the port number for the name as:

tt16       9900/tcp

But still the function getservbyname() returned the port 9898 instead of 9900.

Am I missing something here?