Working on a dice Game in C++

[Josh Ibrahim]

Hello all, I am working on a dice game for my homework in a c++ class. I am suppose to calculate the odds and probability of 2 dice rolls x amount of times and list the probability as rand() error. I have most of the program done but my problem is I can't figure out how to calculate odds and probability for multiple rolls. any suggestions or help would be appreciated
thank you
-Josh Ibrahim

 //Author: Josh Ibrahim, This program takes the user input for number of rolls and simulates the odds/error of two dice rolls
 
 #include <iostream>
 #include <cstdlib>
 #include <ctime>
 
 using namespace std;
 
 int getRoll ();
 
 void displayTotals (int maxRoll,int numberOfRolls);
 
 int main( )
 {
 //sets the seed for the random number
 srand(time(0));
 
 //variables to store user input and dice rolls
 int  numberOfRolls;
 int maxRoll = 0;
 
 
 int loop = 1;
 
 
 cout << "This program rolls two dice and tabulates the results.\n";
 
 while (loop != 0)
 {
 
 
 //ask the user how many rolls of the dice to computer
 cout << "\nEnter Number of Rolls: ";
 cin >>  numberOfRolls;
 
 
 cout<<"\nSum   #Rolled      Odds   %Error";
 
 //for loop calculates odds and %error
displayTotals (maxRoll,numberOfRolls);
 
 
 
 cout << "\nTry again? (1 = Yes, 0 = Exit)";
 cin >> loop;
 
}
 
 
 return 0;
 
 }
 
 
 
 //function takes @numberOfRolls and then calculates possible dice rolls with @maxRoll and displays the outcome. Calls @getRoll
 void displayTotals (int maxRoll,int numberOfRolls)
{
 
 //counters for each dice roll
 int countRoll2 = 0, countRoll3 = 0,countRoll4 = 0,countRoll5 = 0,countRoll6 = 0,countRoll7 = 0;
 int countRoll8 = 0,countRoll9 = 0,countRoll10 = 0,countRoll11= 0,countRoll12= 0;
 
 
 
//calculates dice rolll using a switch
  for ( int i = 0; i < numberOfRolls; i++)
  {
 
  //maxRoll calls get roll twice to grab a psuedorandom number between 2-12     
  maxRoll = getRoll()+ getRoll();
 
  //switch statement counts everytime the "dice" land on a number
      switch (maxRoll)
      {
      case 2:  countRoll2++;
      break;    
      case 3:  countRoll3++;
      break;    
      case 4:   countRoll4++;
      break;    
      case 5:   countRoll5++;
      break;    
      case 6:  countRoll6++;
      break;    
      case 7:  countRoll7++;
      break;    
      case 8:  countRoll8++;
      break;    
      case 9:  countRoll9++;
      break;
      case 10:  countRoll10++;
      break;
      case 11:  countRoll11++;
      break;
      case 12:  countRoll12++;
      break;
      }
 
  }
 
//displays results in order: number of times rolled, odds, %error  
//odds are calculated by: number of total outcomes - total number of unfavorable outcomes
//error is calculated like probabilities:  number of unfavorableoutcomes/totalnumberofoutcomes
 cout <<"\n2:    " << countRoll2<<"             "<< (36) - (35)<<"       "<< (RAND_MAX - 2)/ static_cast < double > (numberOfRolls);
 cout <<"\n3:    " << countRoll3<<"             "<<(36) -  (34)<<"       "<< (RAND_MAX - 3)/ static_cast < double > (numberOfRolls;
 cout <<"\n4:    " << countRoll4<<"             "<<(36) -  (33)<<"       "<< (RAND_MAX - 4)/ static_cast < double > (numberOfRolls);
 cout <<"\n5:    " << countRoll5<<"             "<<(36) -  (32)<<"       "<< (RAND_MAX - 5)/ static_cast < double > (numberOfRolls);
 cout <<"\n6:    " << countRoll6<<"             "<<(36) -  (31)<<"       "<< (RAND_MAX - 6)/ static_cast < double > (numberOfRolls);
 cout <<"\n7:    " << countRoll7<<"             "<<(36) -  (30)<<"       "<< (RAND_MAX - 7)/ static_cast < double > (numberOfRolls);
 cout <<"\n8:    " << countRoll8<<"             "<<(36) -  (31)<<"       "<< (RAND_MAX - 8)/ static_cast < double > (numberOfRolls);
 cout <<"\n9:    " << countRoll9<<"             "<<(36) -  (32)<<"       "<< (RAND_MAX -9)/ static_cast < double > (numberOfRolls);
 cout <<"\n10:   " << countRoll10<<"             "<<(36) - (33)<<"       "<< (RAND_MAX - 10)/ static_cast < double > (numberOfRolls);
 cout <<"\n11:   " << countRoll11<<"             "<<(36) - (34)<<"       "<< (RAND_MAX - 11)/ static_cast < double > (numberOfRolls);
 cout <<"\n12:   " << countRoll12<<"             "<<(36) - (35)<<"       "<< (RAND_MAX - 12)/ static_cast < double > (numberOfRolls);
} 
 
 
//function simulates a diceroll and outputs a number between 1-6 based on system time
int getRoll ()
{
 
 //variable for diceroll
int diceRoll;
 
//dice roll declaration
diceRoll = rand()%6 +1;
 
//returns a number between 2-12
return diceRoll;
}
 

[weaknessforcats]

Probability refers to the "good outcomes". In the case of two dice you get a 7 if the dice roll has any of these 6 combinations:

6 1
5 2
4 3
3 4
2 5
1 6

There are 36 ways two dice can come up so the probability of rolling a 7 is 6/36 or 1/6 (good combinations/all combinations). The odds rolling 3 and 4, in that order is 5/1 (bad combinations/good combinations).

Nothing changes on multiple rolls. If you fly a lot the odds of your plane crashing do not change based on the number of flights. Military pilots who believed they had a greater chance of being shot down the more missions they flew were indulging in a myth.