Bit length of a positive integer in Python

Question

1 = 0b1 -> 1
5 = 0b101 -> 3
10 = 0b1010 -> 4
100 = 0b1100100 -> 7
1000 = 0b1111101000 -> 10
…

How can I get the bit length of an int

Answer 1

Here is another way:

def number_of_bits(n):
    return len('{:b}'.format(n))

Not so efficient I suppose, but doesn't show up in any of the previous answers...