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) {
   int n=16,res=0;
   for(int i=n-1;i>=0;i--)
   res= (res*10)+((num>>i)&1);
   
   if(base==2){ 
    printf("%d",res);
   }   
    else{
        for (int i = 12; i >= 0; i -= 4) {
    int a = (num >> i) & 0xF;
    if (a==0) continue;
    else if (a < 10)
        printf("%d", a);
    else
        printf("%c", 'A' + (a - 10));
}
   }
}

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

    print_base(num, base);
    return 0;
}

Solving Approach