How to Convert a Byte String to an Integer in Python: Which Method is Best?

How to Convert a Byte String to an Integer in Python

Converting a string of bytes into an integer in Python can be achieved using various methods, some of which offer better performance than others.

Built-in Function: int.from_bytes()

In Python versions 3.2 and above, you can directly convert a byte string to an integer using the int.from_bytes() function:

<code class="python">my_int = int.from_bytes(b'y\xcc\xa6\xbb', byteorder='big')</code>

Here, byteorder can be either 'big' or 'little' to specify the endianness of the byte string. Big-endian means the most significant byte is stored first, while little-endian means the least significant byte is stored first.

Using Binary Representation

Another approach is to convert the byte string to its binary representation and then apply the int() function:

<code class="python">my_int = int(''.join(format(byte, '08b') for byte in b'y\xcc\xa6\xbb'[::-1]), 2)</code>

This method is slower than int.from_bytes(), but it can be useful if you need to work with binary data directly.

Custom Function

You can also create your own custom function to convert a byte string to an integer:

<code class="python">def convert_bytes_to_int(byte_string, endianness='big'):
    if endianness == 'big':
        return sum(ord(c) << (i * 8) for i, c in enumerate(byte_string))
    else:
        return sum(ord(c) << (len(byte_string) - i - 1) * 8 for i, c in enumerate(byte_string))</code>

Performance Comparison

The performance of these different methods can vary depending on the length and endianness of the byte string. Generally, int.from_bytes() is the fastest method, followed by the binary representation method and then the custom function.

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