Python bit functions on int with examples

By Ranjeet V

In this tutorial, we are going to learn about some bit functions on int in Python i. e. bit_length(), to_bytes() and from_bytes(). Let’s discuss these functions one by one.

int.bit_length()

This function returns the number of bits required to represent a number in binary. It excludes the sign bit and all the leading zeroes. See the given example code to understand the working of this function.

int1 = 12
print(int1.bit_length())

int2 = 1
print(int2.bit_length())

int3 = -1
print(int3.bit_length())

The output for the example program:

4
1
1

int.to_bytes()

As its name suggests, this function returns an array of bytes that represent an integer. Have a look at the given example code that explains its working.

int1 = 12
print(int1.to_bytes(2, byteorder = 'big'))

int2 = 1
print(int2.to_bytes(2, byteorder = 'big'))

Output:

b'\x00\x0c'
b'\x00\x01'

In the above code, there are two arguments in to_bytes() function. value 2 specifies the length and ‘big’ specifies that the order of bytes is big-endian.

To use this function with negative values we will need to use the third argument as shown below.

int1 = -1
print(int1.to_bytes(2, byteorder = 'big', signed = True))

Output:

b'\xff\xff'

When we make signed  = True, the function accepts negative values, otherwise, it throws an error. The default value for the signed parameter is False.

int.from_bytes()

This is the reverse of the to_bytes() function. It takes an array of bytes as input and converts it into an integer. See the below code.

print(int.from_bytes(b'\x00\x0c', byteorder = 'big'))

print(int.from_bytes(b'\x00\x01', byteorder = 'big'))

Output:

12
1

For negative numbers, make the signed parameter as True as shown here.

print(int.from_bytes(b'\xff\xff', byteorder = 'big', signed = True))

Output:

-1

Hope this article was helpful. Thank you.

Also read: How to Convert a float array to int in Python: NumPy?