How can I improve the functionality of this code [closed]

Answer 1

You can do it using the all() method in python:

a1 = raw_input("Enter an 8 bit  binary number to convert: ")

print all(i in ('0','1') for i in a1)

Answer 2

Use a set:

a1 = input("Enter an 8 bit  binary number to convert: ")

if set(a1) <= set('01'):
    print("Number is binary!")

This will only be true if set(a1) is a subset of set('01'):

>>> set('10011') <= set('01')
True
>>> set('10011abc') <= set('01')
False

You can also just use exceptions (and int() to do the binary -> integer conversion):

try:
    n1 = int(a1, 2)
except ValueError:
    print("Not binary")
else:
    print("Number is binary")
    print("Denary number is: {}".format(n1))

This has the added advantage of converting your binary input to an integer in one step.

If you don't want or can use int(), convert back with a loop and use << left-shift for each binary digit, and | binary bitwise OR to add the new digit:

n1 = 0
for digit in a1:
    n1 = (n1 << 1) | (1 if digit == '1' else 0)

This is rather a round-about way to get the number, but at least you are using binary logic now.