zad 4

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

void setBit(int* mask, int n)
{
    *mask |= (1 << n);
}

void eraseBit(int* mask, int n)
{
    *mask &= ~(1 << n);
}

int isSet(int mask, int n)
{
    return mask & (1 << n);
}

int onesCount(int mask)
{
    int count = 0;
    for (int i = 0; i < sizeof(int) * 8; i++)
    {
        if (isSet(mask, i))
        {
            count++;
        }
    }
    return count;
}

int zerosCount(int mask)
{
    return sizeof(int) * 8 - onesCount(mask);
}

int main()
{
    int prisustviq = 0;
    int option;
    while (1)
    {
        printf("1. Write a presence\n");
        printf("2. Write an absence\n");
        printf("3. Information\n");
        printf("4. Exit\n");
        scanf("%d", &option);
        if (option == 1)
        {
            int n;
            printf("Student number: ");
            scanf("%d", &n);
            setBit(&prisustviq, n);

             if(n >= 32){
        printf("Invalid student number!\n");
    }
        }

        else if (option == 2)
        {
            int n;
            printf("Student number: ");
            scanf("%d", &n);
            eraseBit(&prisustviq, n);

             if(n >= 32){
        printf("Invalid student number!\n");
    }
        }
        else if (option == 3)
        {
            printf("Number of attendance: %d\n", onesCount(prisustviq));
            printf("Number of absences: %d\n", zerosCount(prisustviq));
        }
        else if (option == 4)
        {
            break;
        }else
        {
            printf("Invalid option\n");
        }
    }
    return 0;
}