C PROGRAMMING, PLEASE ADD COMMENTS FOR STEPS

Problem 6.4 Authentification" with files (3 points) Due by Wednesday, March 6th, 10:00 AM Graded manually Write a program which reads from the standard input a username and a password, and prints a message on the screen for granting or denying access depending on the fact if the user and the corresponding password are listed in a file which is given as input to the program. The program should repeatedly check the username and its password introduced from the stan- dard input until the word "exit" is introduced for the username. It is assumed that the word exit" is not contained in the input file. Do not store the whole information (list of usernames and passwords) in the main memory or do not read the whole information from the file for every request, but store only partial information (e.g., the usernames) and use the functions ftell() and fseek () to read the rest of the needed information. You can assume that the content of the input file will be valid if existing. Testcase 6.4: input Testcase 6.4: output Access to user ben is granted. Access to user kate is denied. Access to user bill is granted. Exiting users.txt ben 12b43 kate jfd45 bill iu3556 exit