97. Convert Decimal Number to Binary or Hex Without itoa function

In firmware development, you might need to convert numbers to binary or hexadecimal strings manually — for instance, sending over UART or displaying on an LCD — without using standard library functions like itoa().

Your task is to:

• Read an unsigned integer num and a base (2 or 16)
• Print the number in the given base as a string
• You must not use any standard string conversion like itoa() or sprintf()
• Use only loops and arithmetic

Example-1

Input: num = 10, base = 2
Output: 1010

Example-2

Input: num = 255, base = 16
Output: FF

Example-3

Input: num = 0, base = 2
Output: 0