Convert hex string to int in Python Convert hex string to int in Python python python

Convert hex string to int in Python

Without the 0x prefix, you need to specify the base explicitly, otherwise there's no way to tell:

x = int("deadbeef", 16)

With the 0x prefix, Python can distinguish hex and decimal automatically.

>>> print(int("0xdeadbeef", 0))3735928559>>> print(int("10", 0))10

(You must specify 0 as the base in order to invoke this prefix-guessing behavior; if you omit the second parameter int() will assume base-10.)

int(hexstring, 16) does the trick, and works with and without the 0x prefix:

>>> int("a", 16)10>>> int("0xa", 16)10

Convert hex string to int in Python

I may have it as "0xffff" or just "ffff".

To convert a string to an int, pass the string to int along with the base you are converting from.

Both strings will suffice for conversion in this way:

>>> string_1 = "0xffff">>> string_2 = "ffff">>> int(string_1, 16)65535>>> int(string_2, 16)65535

Letting int infer

If you pass 0 as the base, int will infer the base from the prefix in the string.

>>> int(string_1, 0)65535

Without the hexadecimal prefix, 0x, int does not have enough information with which to guess:

>>> int(string_2, 0)Traceback (most recent call last):  File "<stdin>", line 1, in <module>ValueError: invalid literal for int() with base 0: 'ffff'


If you're typing into source code or an interpreter, Python will make the conversion for you:

>>> integer = 0xffff>>> integer65535

This won't work with ffff because Python will think you're trying to write a legitimate Python name instead:

>>> integer = ffffTraceback (most recent call last):  File "<stdin>", line 1, in <module>NameError: name 'ffff' is not defined

Python numbers start with a numeric character, while Python names cannot start with a numeric character.