CODEWITHSUNDEEP
python-3.x
carcinogenic
carcinogenic

Reputation: 169

Writing a function in Python 3 to convert base 16 to base 10

Is there an easy way to modify this code which converts from base 2 into base 10 to work for converting base 16 into base 10? My objective is to build a dedicated function for conversion and not use any built-in Python features for the calculation. Thanks

BinaryVal = int(input('Enter:')
DecVal = 0
for n in range(len(str(BinaryVal))):
    Power = len(str(BinX))-(n+1)
    DecVal += int(str(BinaryVal)[n])*(2**Power)
print(DecVal)

Upvotes: 4

Views: 13095

Answers (3)

jfs
jfs

Reputation: 414225

To convert hexadecimal string to int:

>>> hexstr = '101010'
>>> int(hexstr, 16)
1052688

The same -- without int constructor:

>>> import binascii 
>>> int.from_bytes(binascii.unhexlify(hexstr), 'big')
1052688

The same -- similar to @SzieberthAdam's answer:

>>> hex2dec = {d: i for i, d in enumerate('0123456789abcdef')}
>>> sum(hex2dec[h] * 16**pos for pos, h in enumerate(reversed(hexstr.lower())))
1052688

or:

>>> from functools import reduce
>>> reduce(lambda n, h: n*16 + hex2dec[h], hexstr.lower(), 0)
1052688

that is equivalent to:

def hex2int(hexstr):
    n = 0
    for h in hexstr.lower():
        n = n*16 + hex2dec[h]
    return n

Example:

>>> hex2int('101010')
1052688

As an alternative, one could convert all digits to int first:

>>> reduce(lambda n, d: n*16 + d, map(hex2dec.get, hexstr.lower()))
1052688

It raises TypeError for empty strings.

Upvotes: 1

SZIEBERTH Ádám
SZIEBERTH Ádám

Reputation: 4184

Well, here you go then:

>>> binary_num = '101010'
>>> sum(int(b)*2**i for i, b in enumerate(reversed(binary_num)))
42

Upvotes: 0

roippi
roippi

Reputation: 25954

Yikes.

int already can convert from any base to base 10 - just supply it as the second argument.

int('101010',2)
Out[64]: 42

int('2A',16)
Out[66]: 42

Upvotes: 4

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