binary_sum.py

import sys

def convertToBinaryString(num):
    if num == 0:
        return "0"

    result = ""
    prevNum = 0
    while abs(num) > 0:
        isOdd = num % 2 != 0
        result = str(int(isOdd)) + result
        prevNum = num
        num //= 2
        # 0 // 2 == 0, thus we terminate
        if prevNum == num:
            break

    if num < 0:
        return "-" + result
    else:
        return result

def bitwiseAdd(num1, num2):
    if num1 == 0:
        return num2
    elif num2 == 0:
        return num1

    uncommonBits = num1 ^ num2
    commonBits = num1 & num2
    # 0 + 0 = 0
    # 0 + 1 = 1
    # 1 + 0 = 1
    # 1 + 1 = 10
    # Thus, we will only ever have to shift over once for carried bits
    carriedBits = commonBits << 1
    return bitwiseAdd(uncommonBits, carriedBits)

def prettyPrintSum(num1, num2, decSum):
    binaryTop = convertToBinaryString(num1)
    binaryBottom = convertToBinaryString(num2)
    # Swap the numbers if the lengths are different.
    # It's nicer if the longer number is on top.
    if len(binaryBottom) > len(binaryTop):
        binaryTop, binaryBottom = binaryBottom, binaryTop

    binarySum = convertToBinaryString(decSum)
    problemSpacing = " " * (len(binaryTop) - len(binaryBottom))
    answerSpacing = " " * (abs(len(binaryTop) + 2 - len(binarySum)))
    dashes = "-" * (len(binaryTop) + 2)
    print(f"  {binaryTop}")
    print(f"+ {problemSpacing}{binaryBottom}")
    print(dashes)
    print(f"{answerSpacing}{binarySum}")
    print(f"\nDec: {decSum}")

if __name__ == "__main__":
    if len(sys.argv) < 3:
        print("Usage: bitwise_add.py num1 num2")
    else:
        dec1 = int(sys.argv[1])
        dec2 = int(sys.argv[2])
        binarySum = bitwiseAdd(dec1, dec2)
        prettyPrintSum(dec1, dec2, binarySum)