Question

C++ programming language, starting out with C++.

Looping Constructs

Write a program to simulate the casino game "craps".
It should execute N number of games so that you can compute the
probability(%) of the "player" winning and the "house" winning.

Probability(%) of the "player" winning = PlayerWins / N * 100.

Probability(%) of the "house" winning = HouseWins / N * 100.

The rules are:

Player rolls two dice.
When the sum is 7 or 11 on first throw, player wins. Game over.
When the sum is 2, 3, or 12 on first throw, "house" wins. Game over.

When the sum is 4,5,6,8,9, or 10 on first throw,
that sum becomes the player's "point".
Now, to win the player must continue rolling the dice until he
matches "point"; however should he roll a 7 then the "house" wins.
That concludes the game.

Run six(6) Simulations to complete the Table:

Number of Games %Prob(PlayerWins) %Prob(HouseWins)
---------------------------------------------------------
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000

Answer 1

// C++ program to simulate the casino game "craps".
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <ctime>
using namespace std;

int main() {

   srand(time(NULL)); // set the seed for random number generator
   int totalGames = 6; // total number of simulations
   int gameNo = 0;
   int numGames[] = {1000, 10000, 100000, 1000000, 10000000, 100000000}; // number of games in each simulation
   int playerWins = 0, houseWins = 0;
   int dice1, dice2, point;

   cout<<left<<setw(20)<<"Number of Games"<<left<<setw(20)<<"%Prob(PlayerWins)"<<left<<setw(20)<<"%Prob(HouseWins)"<<endl;
   // loop that continues till all the simulations are over
   while(gameNo < totalGames)
   {
       // set the playerWins and houseWins to 0 at the start of each simulation
       playerWins = 0;
       houseWins = 0;
       // loop for number of games in that simulation
       for(int i=1;i<=numGames[gameNo];i++)
       {
           // generate the dice roll for 2 die
           dice1 = rand()%6 + 1;
           dice2 = rand()%6 + 1;

           point = dice1 + dice2 ; // get the point

           // sum of die is 7 or 11 in first roll
           if(point == 7 || point == 11)
           {
               playerWins++;
           }else if(point == 2 || point == 3 || point == 12) // sum of die is 2,3 or 12 in first roll
           {
               houseWins++;
           }else
           {
               // loop that continues till the user rolls the point or 7 in subsequent roll
               do
               {
                   dice1 = rand()%6 + 1;
                   dice2 = rand()%6 + 1;

                   if((dice1 + dice2 ) == 7)
                   {
                       houseWins++;
                       break;
                   }
               }while((dice1 + dice2) != point);

               if((dice1+ dice2) == point)
                   playerWins++;
           }
       }

       // output the result of simulation
       cout<<left<<setw(20)<<(numGames[gameNo])<<left<<setw(20)<<(((double)(playerWins))/numGames[gameNo])*100<<left<<setw(20)<<(((double)(houseWins))/numGames[gameNo])*100<<endl;
       gameNo++;
   }

   return 0;
}
//end of program

Output: