How to print values in reverse without the use of arrays nor pointers in C

Question

I've been working on a code that converts a given number (decimal base) to any other base from 2 to 16.

Clearly, I've come across the issue that the function base_conversion_it (it stands for iterative) prints the values in reverse.

I cannot use arrays nor pointers, and everyone on the internet seems to solve this issue like that. My assignment requires making both an iterative and a recursive function (which I did and works).

void base_conversion_it(unsigned int n, unsigned int b) {

    if (n > 0) {

        //bases between 2 and 16
        if (b >= 2 && b <= 16) {

            int r;          //r = remainder
            int q = 1;      //quotient
            int num;        //saves the remainder

            while (q != 0) {

                r = n % b;
                printf("%X", r);

                q = n / b;
                n = q;
            }
        }
    }
}

Answer 1

You start converting from the units digit.
Maybe start with the most significant digit instead?

// It's Undefined Behaviour if `b` is outside the range [2...16]
void base_conversion_it(unsigned int n, unsigned int b) {
    unsigned highestbase = 1;
    while (highestbase * b <= n) highestbase *= b; //possible wrap around and infinite loop

    while (highestbase) {
        printf("%X", n / highestbase);
        n %= highestbase;
        highestbase /= b;
    }
    printf("\n");
}