How can I get Python to use upper case letters when printing hexadecimal values?

Question

In Python v2.6 I can get hexadecimal for my integers in one of two ways:

print(("0x%x")%value)
print(hex(value))

However, in both cases, the hexadecimal digits are lower case. How can I get these in upper case?

Solution 1

Capital X (Python 2 and 3 using sprintf-style formatting):

print("0x%X" % value)

Or in python 3+ (using .format string syntax):

print("0x{:X}".format(value))

Or in python 3.6+ (using formatted string literals):

print(f"0x{value:X}")

Solution 2

Just use upper().

intNum = 1234
hexNum = hex(intNum).upper()
print('Upper hexadecimal number = ', hexNum)

Output:

Upper hexadecimal number =  0X4D2

Solution 3

By using uppercase %X:

>>> print("%X" % 255)
FF

Updating for Python 3.6 era: Just use 'X' in the format part, inside f-strings:

print(f"{255:X}")

(f-strings accept any valid Python expression before the : - including direct numeric expressions and variable names).

Solution 4

print(hex(value).upper().replace('X', 'x'))

Handles negative numbers correctly.

Solution 5

The more Python 3 idiom using f-strings would be:

value = 1234
print(f'0x{value:X}')
'0x4D2'

Notes (and why this is not a duplicate):

• shows how to avoid capitalizing the '0x' prefix, which was an issue in other answers
• shows how to get variable interpolation f'{value}'; nobody actually ever puts (hardcoded) hex literals in real code. There are plenty of pitfalls in doing variable interpolation: it's not f'{x:value}' nor f'{0x:value}' nor f'{value:0x}' nor even f'{value:%x}' as I also tried. So many ways to trip up. It still took me 15 minutes of trial-and-error after rereading four tutorials and whatsnew docs to get the syntax. This answer shows how to get f-string variable interpolation right; others don't.

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Comments

[Peter Mortensen]

But I don't think "0X4D2" is the correct notation. It should be "0x4D2" (lowercase "x").

[smci]

'%X' is best. @PeterMortensen is correct. This way, you'd need something clunky like ''.join([ '0x', hex(value).upper()[2:] ])

[smci]

See my answer for the more Python 3 idiom using f-strings: print(f'0x{value:X}')

[smci]

@wim: No it's not a) jsbueno's answer show neither how to avoid capitalizing the '0x' prefix, nor b) how to get variable interpolation f'{value}'; nobody actually puts hex literals in real code. And there are pitfalls in doing interpolation: it's not f'{x:value}' nor f'{0x:value}' nor f'{value:0x}'. Many ways to trip up. I show how not to.

[smci]

Yes. I'm saying % is the older operator hangover from 2.x which while not officially deprecated, is discouraged. Python 3.6+ finally allows variable interpolation like we've wanted ever since 3.0 and .format().

[Eric]

It's not much of a "Python 3 idiom" if it fails on 6/8 of all released versions of python 3 (although admittedly most are EOL)

[smci]

yes it is, and you're missing the point. This answer is an old near-deprecated 2.x idiom that is only still kept alive in 3.x because they messed up the transition to format() back in 3.0. As of today, "3.x" means "3.6+" or "3.7", where f-strings are awesome. 3.6 was a huge advance for string formatting. People today should be learning f-strings. %-formatting-operator was planned to be deprecated but they got pushback because it's in a lot of legacy code.

[Eric]

'As of today, "3.x" means "3.6+" or "3.7"' - in my experience, this is not true. For me, 3.x means "the earliest version of python 3 that my package will support", which typically is "all non-EOL python 3.x". "where f-strings are awesome" - you're not wrong about that.

[Sean Burton]

All of these give the wrong result if your value is negative. You get 0x-FF when what you want is -0xFF.

[Nathan Garabedian]

Although it seems a little more clunky, this answer is the one that addresses negative numbers and also does not leave X uppercase, but adheres to the standard of x being lowercase. +1