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) {

    if(num == 0) {
        putchar('0');
        return;
    }
    char buff[20];
    int i = 0;
    while(num >0) {
        int rem = num % base;
        if (rem < 10) {
            buff[i++] = rem + '0';
        } else {
            buff[i++] = 'A' + (rem - 10);
        }

        num = num/base;
    }
    for( int j= i-1; j>=0; j--) {
        putchar(buff[j]);
    }
}

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

    print_base(num, base);
    return 0;
}

Solving Approach