Start by assembling the obvious components

We start by assembling the components that jump right out of the statement of requirements:

• We will use Args(C++) for parsing command line options

• We will use Regex(C++) for handling regular expressions

• We will use Time(C++) for time calculations

• We will use String(C++) for the descriptions

• We will use iostream(C++) for input/output

In addition, we will define the application-specific types Appointment and Calendar. Let's put together what we know so far:

       #include <Args.h>
       #include <Regex.h>
       #include <Time.h>
       #include <String.h>
       #include <iostream.h>
       struct Appointment {
           Time time;
           String desc;
       };

       class Calendar { ... };
       main(int argc, const char*const* argv) {
           Calendar cal;
           read_appts(cal);
           process_queries(cal, argc, argv);
       }