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) {
    // Your logic here
    int buffer[20] = {0};
    int i = 0;
    if(base == 16){
        printf("%X", num);
    }else if(base == 2){
        if(num != 0){
            while(num>0){
                buffer[i++] = (num) & (0x01);
                num >>=1;
                //printf("%d", buffer[i-1]);
            }
        }else{
            printf("%d",0);
        }
    }
    for (int j = i-1; j >= 0; j--){
        printf("%d",buffer[j]);
    }
}

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

    print_base(num, base);
    return 0;
}