cho-han bakuchi

Question

I’m trying to make C the game cho-han bakuchi. It is quite simple, the Japanese game consists of throwing two 6-sided dice into a cup, before the dice are shown the player makes the bet saying cho (pairs) or han (odd). Then displays the data and the values are summed.

What I’m missing in my code?

I wouldn’t like the full code, just the point I’m missing so I can make the correction.

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int i,x,apost,cred=100,result=0;

    while(apost!=EOF)
    {
        printf("faça a aposta:(digite -1 para sair)\n");
        scanf("%d", &apost);

        cred=cred-apost;

        printf("escolha 1-cho(par) 2-han(impar):\n");
        scanf("%d", &x);

        switch(getc(x))
        {
            case 1:
                i=2+rand()%12;
                printf("\n%10d", i);

                if(i%2==0)
                {
                    printf("ganhou!\n");
                    cred=cred+(apost*2);
                }

                else
                    printf("perdeu!");

                break;

                case 2:
                    i=2+rand()%12;
                    printf("\n%10d", i);

                    if(i%2!=0)
                    {
                        printf("ganhou!\n");
                        cred=cred+(apost*2);
                    }

                    else
                    printf("perdeu!");
        }

    }

    return 0;
}

Answer 1

Always Compile using warnings! If you use GCC or Clang, pass this option: -Wall to enable all main ones. You can add -Wextra to have even more alerts. They would point out some of the errors that I will list:

1. Uninitialized variable:

   You declared the variable int apost and soon afterwards read its value: while(apost!=EOF). Reading the value of a variable without first giving it a value is invalid, its executable can do anything. In practice, this condition can give true or false in an unpredictable way. Always initialize your variables!

2. Testing EOF in a int:

   apost is an integer, stores the value of the bet. scanf("%d", &apost); reads a number. On the other hand EOF is a char which indicates end of reading and will never be returned by scanf if you asked it a number. Consider using the following logic:

   while (true) {
       int apost;
   
       printf("faça a aposta:(digite -1 para sair)\n");
       scanf("%d", &apost);
   
       if (apost < 0) break;
   
       /* ... */
   }
   

3. getc returns a letter, not a number:

   Understand that '3' nay is the same thing as 3. The first is a letter, which is equivalent to the 53 integer on most systems (ASCII is used). You should test by the letters on your switch, like this: case '1':.

4. Probability distribution:

   The sum of two random numbers from 1 to 6 is different of a random number of 2 to 12. This is because combinations that result in 5, for example, are much more likely than combinations that result in 2. To form 5 we can have: 1+4, 2+3, 3+2, 4+1. Whereas 2 may be only 1+1. So it will be 4 times more likely. This is called the normal distribution. The correction, however, is simple: generate the two values separately and then disappear.