ascii string to sequence of 16-bit values

Question

I'm Python newbie and would like to convert ASCII string into a series of 16-bit values that would put ascii codes of two consecutive characters into MSB and LSB byte of 16 bit value and repeat this for whole string...

I've searched for similar solution but couldn't find any. I'm pretty sure that this is pretty easy task for more experienced Python programmer...

Show us 1) input, 2) desired output, 3) your code, 4) the actual output. — , Apr 16 '14 at 09:23
list of characters from string: ['H', 'e', 'l', 'l', 'o', ',', ' ', 'W', 'o', 'r', 'l', 'd', '!'] sequence of ascii codes: [72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33, 0] desired result(packing pairs of ascii codes into 16-bit values) [a, b, c] where a=72*256+101, b=108*256+111 ... — user2152780, Apr 16 '14 at 09:40

score 0 · Answer 1 · answered Apr 16 '14 at 09:43

0

I think the struct module can be helpful here:

>>> s = 'abcdefg'
>>> if len(s) % 2: s += '\x00'
... 
>>> map(hex, struct.unpack_from("H"*(len(s)//2), s))
['0x6261', '0x6463', '0x6665', '0x67']
>>>

answered Apr 16 '14 at 09:43

gog

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score 0 · Answer 2 · answered Apr 16 '14 at 09:53

I am currently working on the same problem (while learning python) and this is what is working for me – I know it’s not perfect ;( - but still it works ;)

import re

#idea - char to 16
print(format(ord("Z"), "x"))
#idea - 16 to char
print(chr(int("5a", 16)))

string = "some string! Rand0m 0ne!"
hex_string = ''
for c in string:
    hex_string = hex_string + format(ord(c), "x")

del string

print(hex_string)

string_div = re.findall('..', hex_string)
print(re.findall('..', hex_string))

string2 = ''
for c in range(0, (len(hex_string)//2)):
    string2 = string2 + chr(int(string_div[c], 16))

del hex_string
del string_div

print(string2)

laurencevs · Answer 3 · 2014-04-16T10:32:50.737

This definitely worked when I tested it, and isn't too complicated:

string = "Hello, world!"
L = []
for i in string:
    L.append(i) # Makes L the list of characters in the string
for i in range(len(L)):
    L[i] = ord(L[i]) # Converts the characters to their ascii values
output = []
for i in range(len(L)-1):
    if i % 2 == 0:
        output.append((L[i] * 256) + L[i+1]) # Combines pairs as required

with "output" as the list containing the result.

By the way, you can simply use

ord(character)

to get character's ascii value.

I hope this helps you.

score 0 · Accepted Answer · answered Apr 16 '14 at 09:57

In simple Python:

s= 'Hello, World!'
codeList = list()
for c in s:
    codeList.append(ord(c))

print codeList

if len(codeList)%2 > 0:
    codeList.append(0)

finalList = list()
for d in range(0,len(codeList)-1, 2):
    finalList.append(codeList[d]*256+codeList[d+1])

print finalList

If you use list comprehensions:

s= 'Hello, World!'
codeList = [ord(c) for c in s]    
if len(codeList)%2 > 0:    codeList.append(0)
finalList = [codeList[d]*256+codeList[d+1] for d in range(0,len(codeList)-1,2)]

print codeList
print finalList

ascii string to sequence of 16-bit values

4 Answers4