void nullrace(void)
{
  return(0, 0);
}

#include <cstdlib>
#include <iostream>
#include <ctime>

using namespace std;

//function declarations
int main(void);
int menu(void);
int race(int, int);
int moneybet(int);
void nullrace(void);

int money=200;

int main(void)
{
    srand(time(0));
    
    int user_response;
    
    cout<<"welcome to snail races"<<endl;
    while(user_response=menu())
    {
        switch(user_response)
            {
            case 1:
            case 2:
            case 3:
                 ::money += race(moneybet(user_response), user_response);
                 break;
            case 4:nullrace();
                 break; 
            }                          
    }
    return 0;     
}    
int menu(void)
    {
              int user_choice;
              if (money>0)
              {
              cout<<"you have "<<money<<" dollars to bet with.\n";
              
              do
              {
              cout<<"\nwhich snail are u going to bet on?"<<endl
                    <<"[1]snail 1\n"
                    <<"[2]snail 2\n"
                    <<"[3]snail 3\n"
                    <<"[4]just watch\n"
                    <<"[0]exit races\n";
                    
                    cin>>user_choice;
              }
              while (user_choice<0 && user_choice>5);
              
              return user_choice;
              }
              else
              cout<<"you don't have any money to bet with"<<endl
                  <<"Game Over\n" ;
                  system ("pause");
                  return 0;                                  
    }
    
int race(int money, int user_response)
{

    int winner= rand() % 3 + 1 ;
    cout<<"here goes the race\n"
           "the winner is the snail number "<<winner<<endl;
           
           if (winner == user_response)
           {
               cout<<"you win "<<money * 2<<" dollars\n"  ;
               return money *2;        
           }
           else
           cout<<"you have lost your money"<<endl;
           return -1* money;     
}

int moneybet(int userResponse)
{
    int betAmount;
     do
     {
     cout<< "Snail " << userResponse << " is a good choice!"
          << endl;
     cout<< "How much would you like to bet on your snail "
          << userResponse <<"?";
     cin >> betAmount;
     }
     while (betAmount > money);
     return betAmount;
     
}


void nullrace (void)
{
    int winner= rand() % 3 + 1 ;
    cout<<"here goes the race\n"
           "the winner is the snail number "<<winner<<endl;
           return;
}

if( !( cin >> user_choice ) )         // '!' means 'NOT', so when >> returns 
                                      //  false, the following is excecuted!
{
   cout << "The input stream broke!"
           "Numbers only please!" << endl;
   break;                             // jump out of do ... while
}