Allocation of operation in C

Question

I don’t understand why in doing this operation, even though I’ve already declared r as float, if you do not place the cast whether to assign a int.

#include <stdio.h>

void main() {
    float r;
    r = (float) 8 * 2 / 3;
    printf("O resultado eh: %.2f", r); // Sem o cast r= 5.00 que é errado.
}

Answer 1

You don’t need the cast, but you need to use a number indicating that you are a float somehow. Both the 8, as to the 2 as to the 3 are integer numbers, so when he does the calculations they will generate integer numbers, there is no cast implied just because it had a division that could potentially give a decimal part. If you want the decimal part then say this.

#include <stdio.h>

void main() {
    printf("O resultado eh: %.2f", 8.0 * 2.0 / 3.0);
}

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

Need to put the decimal part in all? In this case does not need, but has case that may need because of precedence and associativity. If you’re working with float use literals that are already float.