Converting binary to decimal integer output

Question

Hello, all. I can able to solve how to convert a decimal to a binary number. But, If you ask me to convert binary number to decimal, I will just say I don't know how to do it. Is there any way of solving this question without using built-in functions?

Thanks in advance.

Answer 1

Try to use int & set the base as 2 (In case of binary):

>>> binary = raw_input('enter a number: ')

enter a number: 11001

>>> int(binary, 2)

25

>>>

If you don't want to use int, try:

binary = raw_input('enter a number: ')

decimal = 0

for digit in binary:

    decimal = decimal*2 + int(digit)

print decimal

Look at the demonstration:

>>> binary = raw_input('enter a number: ')

enter a number: 11001

>>> decimal = 0

>>> for digit in binary:

...     decimal = decimal*2 + int(digit)

...

>>> print decimal

25

>>>

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