Format hex digits for character code \x

Question

I'm new to Python's \x00 string formatting and I was wondering if there is a nice pythonic way of doing something like below? I would like to dynamically insert the \x formatting into my python strings.

# Is there a way get a similar effect to this?

s = "commandstring \x{}\x{}".format('00', '00')
s = "commandstring \x%s\x%s" % ('00', '00')

Some of my strings will be regular text and numbers, but I also need to insert the Hex values

Answer 1

\x00 represents a single byte. Produce those single bytes directly:

>>> "commandstring {}{}".format('\x00', '\x00')
'commandstring \x00\x00'

or use the chr() function to produce the byte given an integer:

>>> "commandstring {}{}".format(chr(0), chr(0))
'commandstring \x00\x00'

The \xhh notation is syntax that can only be used in a string literal. You could construct the syntax then have Python explicitly interpret that with eval(), ast.literal_eval or the raw_string codec, but that is usually not what you need in the first place.

Answer 2

I think what you want here is the %x placeholder. Try the following:

s = "commandstring \x%x\x%x" % (50, 95)

It will give you

s = "commandstring \x32\x5f"

But, you need to pass integers for it to work.