System() with a variable?

If I ask for a user to enter a username (txtuser) ... BOB and then use that for a port how do I run the following?

system("lpadmin -p printer -v ipp://server/txtuser -E -P /path to driver");

 

I know how to do that. I was just wondering if there is an easier way to do it without creating another variable kinda like

system("lpadmin -p printer -v ipp://server/" + txtuser + "-E -P /path to driver");

or something