Python convert decimal to hex

Question

I have a function here that converts decimal to hex but it prints it in reverse order. How would I fix it?

def ChangeHex(n):
    if (n < 0):
        print(0)
    elif (n<=1):
        print(n)
    else:
        x =(n%16)
        if (x < 10):
            print(x), 
        if (x == 10):
            print("A"),
        if (x == 11):
            print("B"),
        if (x == 12):
            print("C"),
        if (x == 13):
            print("D"),
        if (x == 14):
            print("E"),
        if (x == 15):
            print ("F"),
        ChangeHex( n / 16 )

Solution 1

If you want to code this yourself instead of using the built-in function hex(), you can simply do the recursive call before you print the current digit:

def ChangeHex(n):
    if (n < 0):
        print(0)
    elif (n<=1):
        print n,
    else:
        ChangeHex( n / 16 )
        x =(n%16)
        if (x < 10):
            print(x), 
        if (x == 10):
            print("A"),
        if (x == 11):
            print("B"),
        if (x == 12):
            print("C"),
        if (x == 13):
            print("D"),
        if (x == 14):
            print("E"),
        if (x == 15):
            print ("F"),

Solution 2

What about this:

hex(dec).split('x')[-1]

Example:

>>> d = 30
>>> hex(d).split('x')[-1]
'1e'

~Rich

By using -1 in the result of split(), this would work even if split returned a list of 1 element.

Solution 3

This isn't exactly what you asked for but you can use the "hex" function in python:

>>> hex(15)
'0xf'

Solution 4

I think this solution is elegant:

def toHex(dec):
    digits = "0123456789ABCDEF"
    x = (dec % 16)
    rest = dec // 16
    if (rest == 0):
        return digits[x]
    return toHex(rest) + digits[x]

numbers = [0, 11, 16, 32, 33, 41, 45, 678, 574893]
print [toHex(x) for x in numbers]
print [hex(x) for x in numbers]

This output:

['0', 'B', '10', '20', '21', '29', '2D', '2A6', '8C5AD']
['0x0', '0xb', '0x10', '0x20', '0x21', '0x29', '0x2d', '0x2a6', '0x8c5ad']

Solution 5

I use

"0x%X" % n

where n is the decimal number to convert.

View more solutions

Comments

[Moirisa Dikaiosýni]

print hex(15); TypeError: 'str' object is not callable

[Zizouz212]

@Babbit Then you're doing something wrong. You probably named a variable hex or something.

[Martin Thoma]

See also: Python: hex conversion always two digits

[Sven Marnach]

@Apostolos No, I don't think it is. What makes you think so? However, I think it's useful for the original poster of the question to learn how to fix their code, even though it's not the solution i'd recommend to go with in "real" code.

[sortas]

ChangeHex( n / 16 ) or ChangeHex( n // 16 ) ?

[Sven Marnach]

@sortas n // 16 in Python 3. This answer was written for Python 2, and in that version the two are equivalent. (I tried to make the minimal change to the code in the question to make it work.)

[Germa Vinsmoke]

stackoverflow.com/a/35750576/8437974 Martijn Pieter's format(15, 'x')

[Meto]

Perfect solution, plus the examples. Thank you sir.

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