The while loop doesn’t stop on a boolean condition

Question

I wrote a simple code to solve an artificial problem. I want the program to exit the loop body after N =< 3, but the iterations continue after the condition isn't met. Where did i go wrong?

int main(){

    uint8_t N = 0;
    int power = 1;
    std::cin >> N;

    while (N >= 4){
        power *= 3;
        N -= 3;
    }
        
    power *= N;
    std::cout << power;
    
    return 0;
}

gcc 12.2.0. Flags -Wall -O2

I tried to use a loop for (N; N >= 4; N -=3), but result didn't change.

[What is a debugger and how can it help me diagnose problems?](https://stackoverflow.com/questions/25385173/what-is-a-debugger-and-how-can-it-help-me-diagnose-problems). — Jason, Nov 03 '22 at 09:14
please be more exact. What is the value of `N` that makes the loop not stop? If you enter `2` then after decrementing the value by 3 it is never `<4`. If `N` you enter is `>4` its a different story. Details matter. Please add example input in the question when thats required to reprduce the issue — 463035818_is_not_an_ai, Nov 03 '22 at 09:41
@niu2x unsigneds don't overflow, they wrap around, but yeah thats most likely the reason — 463035818_is_not_an_ai, Nov 03 '22 at 09:42
@463035818_is_not_a_number if 2 is entered, the loop won't start, so power will be 2. As already commented, the bug is not reproducible. — stefaanv, Nov 03 '22 at 09:43
@463035818_is_not_a_number I I put the loop inside the `if (N > 4)` condition, but the result didn't change. For example, I want the output to be `18` when I enter `8`. — Fidelity, Nov 03 '22 at 09:49

score 3 · Accepted Answer · edited Nov 03 '22 at 09:53

3

uint8_t is char type.

In stdint.h,

typedef unsigned char      uint8_t;

'4' will be resulted in integer 52 due to implicit casting.

You may just use int type if you are accepting number.

edited Nov 03 '22 at 09:53

463035818_is_not_an_ai

109,796
11
89
185

answered Nov 03 '22 at 09:45

Aung

191
1
4

Thank you, problem solved. When I looked at the values of the debugger, I could not understand why it was adding characters to N. – Fidelity Nov 03 '22 at 09:54

The while loop doesn’t stop on a boolean condition

1 Answers1