The hex() function in python, puts the leading characters 0x in front of the number. Is there anyway to tell it NOT to put them? So 0xfa230 will be fa230.

The code is

import fileinput
f = open('hexa', 'w')
for line in fileinput.input(['pattern0.txt']):
   f.write(hex(int(line)))
   f.write('\n')

(Recommended)

Python 3 f-strings: Answered by @GringoSuave

>>> i = 3735928559
>>> f'{i:x}'
'deadbeef'

---

Alternatives:

format builtin function (good for single values only)

>>> format(3735928559, 'x')
'deadbeef'

And sometimes we still may need to use str.format formatting in certain situations @Eumiro

(Though I would still recommend f-strings in most situations)

>>> '{:x}'.format(3735928559)
'deadbeef'

(Legacy) f-strings should solve all of your needs, but printf-style formatting is what we used to do @msvalkon

>>> '%x' % 3735928559
'deadbeef'

Without string formatting @jsbueno

>>> i = 3735928559
>>> i.to_bytes(4, "big").hex()
'deadbeef'

Hacky Answers (avoid)

hex(i)[2:] @GuillaumeLemaître

>>> i = 3735928559
>>> hex(i)[2:]
'deadbeef'

This relies on string slicing instead of using a function / method made specifically for formatting as hex. This is why it may give unexpected output for negative numbers:

>>> i = -3735928559
>>> hex(i)[2:]
'xdeadbeef'
>>> f'{i:x}'
'-deadbeef'