//====================================================== file = coinSim.c =====
//=  Simulation of flipping a coin                                            =
//=============================================================================
//=  Notes:                                                                   =
//=    1) This program is a class example for CAP 4800 (Simulation) for       =
//=       Summer 2013. This is an example of a Monte Carlo simulation.        =
//=    2) See NUM_FLIP and TRACE in the #define section                       =
//=    3) Ignore two warnings on always false and unreachable code            =
//=---------------------------------------------------------------------------=
//=  Build: bcc32 coinSim.c, cl coinSim.c, gcc coinSim.c -o coinSim           =
//=---------------------------------------------------------------------------=
//=  Execute: coinSim                                                         =
//=---------------------------------------------------------------------------=
//=  Sample execution:                                                        =
//=                                                                           =
//=---------------------------------------------------------------------------=
//=  History: KJC (05/20/13) - Genesis                                        =
//=============================================================================
//----- Include files ---------------------------------------------------------
#include <stdio.h>            // Needed for printf()
#include <stdlib.h>           // Needed for rand()

//----- Constants -------------------------------------------------------------
#define    FALSE       0      // Boolean false
#define     TRUE       1      // Boolean true
#define     HEAD       0      // Define head as a 0
#define     TAIL       1      // Define tail as a 1

#define NUM_FLIP  1000000     // Number of iterations to simulate
#define    TRACE    FALSE     // Enable or disable trace

//===== Main program ==========================================================
void main(void)
{
  int    coinFace;        // Value of coin face (HEAD or TAIL)
  int    headCount;       // Count of event head occurring
  int    i;               // Loop counter

  // Output a "running" banner
  printf(">>> The simulation is running... \n");

  // Run the simulation for NUM_FLIP coin flips
  headCount = 0;
  for (i=0; i<NUM_FLIP; i++)
  {
    // Flip the coin with resulting value being a HEAD or TAIL
    coinFace = rand() % 2;

    // Check if head (our desired outcome) and increment headCount if so
    if (coinFace == HEAD)
      headCount++;
  }

  // Output results
  printf("=============================================================== \n");
  printf("==          *** Simulation of flipping a coin ***            == \n");
  printf("=============================================================== \n");
  printf("=  MODEL INPUT:                                                 \n");
  printf("=    Number of coin flips = %d    \n", NUM_FLIP);
  printf("=============================================================== \n");
  printf("=  MODEL OUTPUT:                                                \n");
  printf("=    Percent heads        = %f %% \n", 100.0 * headCount / NUM_FLIP);
  printf("=============================================================== \n");
}