Convert Decimal Number to Binary or Hex Without itoa function

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

void print_base(uint16_t num, uint8_t base) {
    if (num==0){
        printf ("0");
        return;
    }
    char buffer[16];
    int i = 0;
    char hex_chars[] = "0123456789ABCDEF";
    while (num>0) {
        int remainder = num % base;
        buffer[i++] = hex_chars[remainder];
        num/=base;
    }
    for (int j = i-1; j >= 0; j--) {
        printf ("%c", buffer[j]);
    }
}

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

    print_base(num, base);
    return 0;
}