Thread: creating a filename based on a variable

I'm writing some code that will create an XML file based on a logged in users id number ie: 04390 will create 04390.xml and so forth. I have some code like this...

Code:

int studentID;


yada yada yada

ofstream fout("//ID BASED FILE NAME HERE")

how can i control what will go in that commented area marked "id based file name here"?
i don't want to hard code in a lot of

Code:

switch (studentID) {
            case 04390:
                     ofstream fout("04390.xml");
                     break;
            }

so does anybody have any bright ideas on how do accomplish my goal?? if anyone can help it would be greatly appreciated. thanks