decimal_to_binary.py

"""Convert a Decimal Number to a Binary Number."""


defdecimal_to_binary_iterative(num: int) ->str:
"""
 Convert an Integer Decimal Number to a Binary Number as str.
 >>> decimal_to_binary_iterative(0)
 '0b0'
 >>> decimal_to_binary_iterative(2)
 '0b10'
 >>> decimal_to_binary_iterative(7)
 '0b111'
 >>> decimal_to_binary_iterative(35)
 '0b100011'
 >>> # negatives work too
 >>> decimal_to_binary_iterative(-2)
 '-0b10'
 >>> # other floats will error
 >>> decimal_to_binary_iterative(16.16) # doctest: +ELLIPSIS
 Traceback (most recent call last):
 ...
 TypeError: 'float' object cannot be interpreted as an integer
 >>> # strings will error as well
 >>> decimal_to_binary_iterative('0xfffff') # doctest: +ELLIPSIS
 Traceback (most recent call last):
 ...
 TypeError: 'str' object cannot be interpreted as an integer
 """

ifisinstance(num, float):
raiseTypeError("'float' object cannot be interpreted as an integer")
ifisinstance(num, str):
raiseTypeError("'str' object cannot be interpreted as an integer")

ifnum==0:
return"0b0"

negative=False

ifnum<0:
negative=True
num=-num

binary: list[int] = []
whilenum>0:
binary.insert(0, num%2)
num>>=1

ifnegative:
return"-0b"+"".join(str(e) foreinbinary)

return"0b"+"".join(str(e) foreinbinary)


defdecimal_to_binary_recursive_helper(decimal: int) ->str:
"""
 Take a positive integer value and return its binary equivalent.
 >>> decimal_to_binary_recursive_helper(1000)
 '1111101000'
 >>> decimal_to_binary_recursive_helper("72")
 '1001000'
 >>> decimal_to_binary_recursive_helper("number")
 Traceback (most recent call last):
 ...
 ValueError: invalid literal for int() with base 10: 'number'
 """
decimal=int(decimal)
ifdecimalin (0, 1): # Exit cases for the recursion
returnstr(decimal)
div, mod=divmod(decimal, 2)
returndecimal_to_binary_recursive_helper(div) +str(mod)


defdecimal_to_binary_recursive(number: str) ->str:
"""
 Take an integer value and raise ValueError for wrong inputs,
 call the function above and return the output with prefix "0b" & "-0b"
 for positive and negative integers respectively.
 >>> decimal_to_binary_recursive(0)
 '0b0'
 >>> decimal_to_binary_recursive(40)
 '0b101000'
 >>> decimal_to_binary_recursive(-40)
 '-0b101000'
 >>> decimal_to_binary_recursive(40.8)
 Traceback (most recent call last):
 ...
 ValueError: Input value is not an integer
 >>> decimal_to_binary_recursive("forty")
 Traceback (most recent call last):
 ...
 ValueError: Input value is not an integer
 """
number=str(number).strip()
ifnotnumber:
raiseValueError("No input value was provided")
negative="-"ifnumber.startswith("-") else""
number=number.lstrip("-")
ifnotnumber.isnumeric():
raiseValueError("Input value is not an integer")
returnf"{negative}0b{decimal_to_binary_recursive_helper(int(number))}"


if__name__=="__main__":
importdoctest

doctest.testmod()

print(decimal_to_binary_recursive(input("Input a decimal number: ")))