HomeWork C Day4

#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);
}

void IsHere(int mask){
    for(int i =0; i < sizeof(int) * 8; i++){
        if(isSet(mask, i)){
            printf("\nStudent %d attends\n", i);
        }else{
            printf("\nStudent %d is absent\n", i);
        }
    }
}

int IsNotHere(int mask, int n){
    return isSet(mask, n) ? 0 : 1;
}

int Validation(int n){
    return n > 32 || n < 0 ? 0 : 1;
}

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. Check presence/absence by number (reversed)\n");
        printf("5. Exit\n");

        printf("Enter option: ");
        scanf("%d", &option);


        if (option == 1){
            int n;
            printf("Student number: ");
            scanf("%d", &n);

            if(Validation(n)){
                setBit(&prisustviq, n);
            }else{
               printf("Invalid number\n");
            }
        }else if (option == 2){
            int n;
            printf("Student number: ");
            scanf("%d", &n);

            if(Validation(n)){
                eraseBit(&prisustviq, n);
            }else{
               printf("Invalid number\n");
            }
        }else if (option == 3){
            printf("Number of attendees: %d\n", onesCount(prisustviq));
            printf("Number of absentees: %d\n", zerosCount(prisustviq));
            IsHere(prisustviq);
        }else if (option == 4){
            int n;
            printf("Student number: ");
            scanf("%d", &n);

            if(Validation(n)){
               if(IsNotHere(prisustviq, n)){
                    printf("Student %d attends\n", n);
                }else{
                    printf("Student %d is absent\n", n);
                }
            }else{
                printf("Invalid number\n");
            }
       }else if(option == 5){
            break;
       }else{
            printf("Invalid command \n");
        }
    }
    return 0;
}