#include "library.h"

int formula(int x, int y)
{ return x*y; }    // this is an absolutely trivial function, just an illustration.
                   // a function can do anything. It allows an otherwise meaningless
                   // formula to be given a meaningful name, and it allows a very
                   // complicated formula to just be typed once but used many times
                   // without risk of mistakes slipping in.

void cajole(int a, int b)
                   // a and b are just the names that this function uses to refer to
                   // its inputs. They are meaningless outside the function
{ print("Obey me and I will allow ");
  print(a);
  print(" times ");
  print(b);
  print(" to remain ");
  const int answer = formula(a, b);  // the values of a and b are given to "formula"
                                     // as its inputs. "formula" doesn't know or care
                                     // where its inputs came from. It just knows them
                                     // as x and y.
  if (answer % 10 == 2)
    print("forbidden.\n");
  else if (answer >= 100)
    print("too big for you to worry about.\n");
  else
  { print(answer);
    print(" for ever.\n"); } }

void main()
{ print("Greetings, human!\n");
  cajole(6, 9);   // 6 and 9 are given as the inputs to "cajole", who refers
                  // to them as a and b
  cajole(8, 9);
  cajole(12, 13);
  cajole(7, 9);
  cajole(1+2+3, 9+8+7);
  print("Get on with your work\n"); }