Python ValueError: chr() arg not in range(256)

Question

So I am learning python and redoing some old projects. This project involves taking in a dictionary and a message to be translated from the command line, and translating the message. (For example: "btw, hello how r u" would be translated to "by the way, hello how are you".

We are using a scanner supplied by the professor to read in tokens and strings. If necessary I can post it here too. Heres my error:

Nathans-Air-4:py1 Nathan$ python translate.py test.xlt test.msg
Traceback (most recent call last):
  File "translate.py", line 26, in <module>
    main()
  File "translate.py", line 13, in main
    dictionary,count = makeDictionary(commandDict)
  File "/Users/Nathan/cs150/extra/py1/support.py", line 12, in makeDictionary
    string = s.readstring()
  File "/Users/Nathan/cs150/extra/py1/scanner.py", line 105, in readstring
    return self._getString()
  File "/Users/Nathan/cs150/extra/py1/scanner.py", line 251, in _getString
    if (delimiter == chr(0x2018)):
ValueError: chr() arg not in range(256)

Heres my main translate.py file:

from support import *
from scanner import *
import sys

def main():
    arguments = len(sys.argv)
    if arguments != 3:
        print'Need two arguments!\n'
        exit(1)
    commandDict = sys.argv[1]
    commandMessage = sys.argv[2]

    dictionary,count = makeDictionary(commandDict)

    message,messageCount = makeMessage(commandMessage)

    print(dictionary)
    print(message)

    i = 0
    while count < messageCount:
        translation = translate(message[i],dictionary,messageCount)
        print(translation)
        count = count + 1
        i = i +1
    main()

And here is my support.py file I am using...

from scanner import *

def makeDictionary(filename):
    fp = open(filename,"r")

    s = Scanner(filename)
    lyst = []
    token = s.readtoken()
    count = 0
    while (token != ""):
        lyst.append(token)
        string = s.readstring()
        count = count+1
        lyst.append(string)
        token = s.readtoken()
    return lyst,count

def translate(word,dictionary,count):
    i = 0
    while i != count:
        if word == dictionary[i]:
            return dictionary[i+1]
            i = i+1
        else:
            return word
            i = i+1
    return 0

def makeMessage(filename):
    fp = open(filename,"r")

    s = Scanner(filename)
    lyst2 = []
    string = s.readtoken()
    count = 0
    while (string != ""):
        lyst2.append(string)
        string = s.readtoken()
        count = count +  1
    return lyst2,count

Does anyone know whats going on here? I've looked through several times and i dont know why readString is throwing this error... Its probably something stupid i missed

Answer 1

chr(0x2018) will work if you use Python 3.

You have code that's written for Python 3 but you run it with Python 2. In Python 2 chr will give you a one character string in the ASCII range. This is an 8-bit string, so the maximum parameter value for chris 255. In Python 3 you'll get a unicode character and unicode code points can go up to much higher values.