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) {
    uint32_t div=num;
    int i=0;
    int arr[16];
    uint32_t rem;
    if(base==2)
    { 
        do 
        {
         
        if((num & 0x1)==1)
        {
           arr[i]=1;
        }
        else
        {
            arr[i]=0;
        }
           num=num>>1;
           i++;
        }while(num!=0);
        
        for(int x=i-1;x>=0;x--)
        {
            printf("%d",arr[x]);
        }
    }

    else
    {
        
        while(div!=0)
        {
        rem=div%16;
        div=div/16;
        num=num|(rem<<4*i);
        i++;
        }
        printf("%X",num);
    }
}

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

    print_base(num, base);
    return 0;
}

Solving Approach