Negative, positive and zero numbers do not return as expected

Question

The code is ignoring the type variable int and is receiving real values.

Also, when I enter a character it returns that is zero and not that it is not a valid number.

Identify whether it is positive, negative or zero works.

int main(void){
    int Num;

    printf("Digite um numero inteiro: ");
    scanf("%f", &Num);

    if(Num > 0){
        printf("O numero e positivo");
    }else if(Num < 0){
        printf("O numero e negativo");
    }else if(Num == 0){
        printf("O numero e zero");
    }else{
        printf("Nao e um numero valido");
    }
}

Answer 1

If you are programming in C (the question is C++), you should use the input formatter %d. but even not doing this is not to give any problem in any compiler (some will prevent compiling, but if compiling it will still take the whole part of typing). I took out the unnecessary parts of the code and formatted it better. I didn’t make any major validations, if something invalid is typed it won’t fall into else how are you finding (see more):

int main(void) {
    int num;
    printf("Digite um numero inteiro: ");
    scanf("%d", &num);
    if (num > 0) printf("O numero e positivo");
    else if (num < 0) printf("O numero e negativo");
    else if (num == 0) printf("O numero e zero");
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

If you are using C++ even suggest then use cin and cout and you won’t have these problems.