[Tutor] Changing a string number to another number [RESOLVED]

[Ken G.]

On 04/15/2015 08:50 AM, Peter Otten wrote:
> Ken G. wrote:
>
>> When running the following code, I get the following
>> error code:
>>
>> 201504110102030405061
>> Traceback (most recent call last):
>>     File "Mega_Millions_Tickets_Change.py", line 11, in <module>
>>       datecode[20:21] = "0"
>> TypeError: 'str' object does not support item assignment
>>
>>
>> datecode = "201504110102030405061"
>> print datecode
>> if datecode[20:21] == "1":
>>       datecode[20:21] = "0"
>> print datecode
>>
>>
>> I have tried using the zero as an integer but still get the same error
>> code. Any suggestion?
> Strings in Python are "immutable", i. e. you cannot change them once they
> are created. Instead you have to construct a new string. In the general case
> you can get the same effect as replacing the character #n of an all-ascii
> string with
>
>>>> s = "01234567890"
>>>> n = 3
>>>> s[:n] + "x" + s[n+1:]
> '012x4567890'
>
> In your case you want to replace the last character, so s[n+1:] is empty
>
>>>> s = "201504110102030405061"
>>>> n = 20
>>>> s[n+1:]
> ''
>
> and just
>
>>>> s[:n] + "x"
> '20150411010203040506x'
>
> is sufficient. A word of warning: as you are using Python 2 you are actually
> manipulating bytes not characters when using the default string type. This
> may have ugly consequences:
>
>>>> s = "ähnlich" # I'm using UTF-8
>>>> print "ae" + s[1:]
> ae�hnlich
>
> Here the new string is not valid UTF-8 because in that encoding a-umlaut
> consists of two bytes and I'm only removing one of them.
>
> A partial fix is to use unicode explicitly:
>
>>>> s = u"ähnlich"
>>>> print "ae" + s[1:]
> aehnlich
>
> But if you are just starting consider switching to Python 3 where unicode is
> the default string type.
>
Thank you, Peter. That would be something for me to consider.
Alas, I am still using Python 2.7.6 but do have it on standby.

Again, thanks.

Ken