Question

Undecimal to decimal&decimal to undecimal

#Your code here

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Binary-to-Decimal In a previous lab, we considered converting a byte string to decimal. What about converting a binary string of arbitrary length to decimal? Given a binary string of an arbitrarily length k, bk-1....bi .box the decimal number can be computed by the formula 20 .bo +21.b, + ... + 2k-1. bx-1- In mathematics, we use the summation notation to write the above formula: k- 2.b; i=0) In a program, the formula can be implemented as a for loop: def binary_to_decimal(binary_str): k = len(binary_str) decimal = 0 # initialization for i in range(k): decimal += 2**i * int(binary_str[(k-1)-i]) # iteration return decimal Note that bị is given by binary_str[(k-1)-i]: binary-str bk-1 indexing [0] bi-2 [1] 1 [k - 1]

Answer 1

def undecimal_to_decimal(undecimal_str):

    decimal = 0
    n = len(undecimal_str)

    # Similar to decimal where we add powers of 10 multiplied with digit at position i,
    # in undecimal we do it with 11.
    # Power of 11 at position i in string is n-1-i (where n is length of string).
    # So we need to do summation of digit(i) * (11 ^ (n-1-i)) where i is from 0 to n-1.
    for i in range(n):
        num = -1
        if(undecimal_str[i] != "X"):
            num = int(undecimal_str[i])
        else:
            num = 10
        
        decimal += num*(pow(11,n-1-i))
    
    return decimal

def decimal_to_undecimal(decimal):
    undecimal_str = ""

    # Similar to binary, to convert to undecimal, at each step we find the remainder of decimal with 11,
    # add the remainder to the undecimal string and divide the decimal by 11.
    # Doing this we get each digit of undecimal string.
    while(decimal != 0):
        rem = decimal % 11
        decimal = decimal//11

        if(rem == 10):
            undecimal_str = "X" + undecimal_str
        else:
            undecimal_str = str(rem) + undecimal_str
    
    return undecimal_str

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