Convert Decimal Number to Binary or Hex Without itoa function

Code

#include <stdio.h>
#include <stdint.h>

void print_base(uint16_t num, uint8_t base) {
    uint8_t res[16] = {0};
    int index = 0;

    if(num == 0){
        printf("0");
        return;
    }

    if(base == 2){
        while(num){
            res[index] = (num % 2);
            num /= 2;
            index++;
        }
        for(int i = index - 1; i >= 0; i--){
            printf("%d", res[i]);
        }
    }
    else if(base == 16){
        while(num){
            res[index] = (num % 16);
            num /= 16;
            index++;
        }
        for(int i = index - 1; i >= 0; i--){
            if(res[i] >= 10){
                printf("%c",('A' + (res[i] - 10)));
            }
            else{
                printf("%d", res[i]);
            }
        }
    }
}

int main() {
    uint16_t num;
    uint8_t base;
    scanf("%hu %hhu", &num, &base);

    print_base(num, base);
    return 0;
}

/*

10 / 2 = 5 0
5 / 2 = 2 1
2 / 2 = 1 0
1 / 2 = 0 1

*/

Solving Approach