How to use the Python hex() function?

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Python Hex Method

In this article, we’ll cover the Python hex() function.

This function is useful if you want to convert an Integer to a hexadecimal string, prefixed with “0x”.

Let’s look at how we could use this function.

Using the Python hex() function

The Python hex() function has a very simple syntax:

hex_string = hex(val)

Here, val can be an Integer, binary, octal, or a hexadecimal number.

Let’s look at some examples quickly.

print(hex(1000))  # decimal
print(hex(0b111))  # binary
print(hex(0o77))  # octal
print(hex(0XFF))  # hexadecimal

Output

0x3e8
0x7
0x3f
0xff

Using Python hex() on a custom object

We can also use hex() on a custom object. But, if we want to use it successfully, we must define the __index__() dunder method for our class.

The hex() method will call __index__(), so we must implement it. This must return a value, which can be a decimal / binary / octal / hexadecimal number.

class MyClass:
    def __init__(self, value):
        self.value = value
    def __index__(self):
        print('__index__() dunder method called')
        return self.value


my_obj = MyClass(255)

print(hex(my_obj))

Output

__index__() dunder method called
0xff

Indeed, as you can see, it returns what we expected.

First, hex() calls the __index__ method on our custom class.

Then, it converts the returned value to a hexadecimal string (255 -> “0xff”)

Conclusion

In this article, we learned about using the hex() function, to convert numerical values into a hexadecimal string.

References

  • JournalDev article on Python hex()