Description for each program

1. 0-main.c,
   • The program will create 0-main.c and main.h to test that the function positive_or_negative() gives the correct output when given a case of 0.
2. 1-main.c
   • Comment out (don’t delete it!) the part of the code that is causing the output to go into an infinite loop.
3. 2-largest_number.c
   • A program prints the largest of three integers.
4. 3-print_remaining_days.c
   • Fix the print_remaining_days() function so that the output works correctly for all dates and all leap years.