[Tutor] Changing a string number to another number

[Dave Angel]

On 04/15/2015 08:21 AM, 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

A 'str' object is immutable, which means simply that you cannot modify 
it in place.  All you can do is create a new str object, and rebind your 
variable to that new one.  That means that there are a number of things 
you cannot do directly to a string.  One of them is modifying a slice, 
as you're trying to do.

>
>
> datecode = "201504110102030405061"
> print datecode
> if datecode[20:21] == "1":
>      datecode[20:21] = "0"
> print datecode
>
>

I can see that the first part of this is probably a standard datetime, 
and might suggest you convert it to one, and modify that as needed.  But 
you're so far to the right that I have to figure you're doing some 
custom encoding.

If you just want to replace a single character of a string, you could 
use the construct:

datecode = datecode[:20] + "0" + datecode[21:]

If you need something fancier, perhaps you can generalize it.

-- 
DaveA