Changing out_filename based of input

Hi everyone, In my exam I've been given a task to read list from file and to create another file which would be output file. In the task it says that out_filaname should be changed based on input(in this specific case if I type "./task USA Friends 1994" as my call of program it should create file named USA.txt) So basicly whichever country I put in call, program should create country.txt file. How do I code that part of my program?

You need to construct the filename from the command line argument, e.g., by creating an array of char large enough to hold the result, then copying the command line argument followed by ".txt".