Charles Hixson wrote:
> python3 --version
> Python 3.5.3
>
> Running on Debian stretch
>
> In this code s is a string parameter
>
> while (j < k and \
> (s[j].isalnum()) or \
> (s[j] in seps and s[j+1].isalnum()) ):
> j = j + 1
> print ("i = {0}, j = {1}, k = {2}, len[s] = {3}". \
> format(i, j, k, len(s) ) )
>
> Yields the result:
>
> i = 25, j = 27, k = 31, len[s] = 32
> i = 25, j = 28, k = 31, len[s] = 32
> i = 25, j = 29, k = 31, len[s] = 32
> i = 25, j = 30, k = 31, len[s] = 32
> i = 25, j = 31, k = 31, len[s] = 32
> Traceback (most recent call last):
> File "parse1.py", line 40, in <module>
> print (parse1("The gostack distimms the doshes."))
> File "parse1.py", line 21, in parse1
> (s[j] in seps and s[j+1].isalnum()) ):
> IndexError: string index out of range
>
> I hesitate to report this, because I've been wrong so often, but it
> looks to me like the last iteration should not have happened since j is
> not less than k.
You have made a bit of a mess of the while condition. Removing random space
and newlines:
(j < k and (s[j].isalnum()) or (s[j] in seps and s[j+1].isalnum()))
The structure is
a and b or (c and d) # a: j<k
# b: (s[j].isalnum())
# c: s[j] in seps
# d: s[j+1].isalnum()
which is evalued as
(a and b) or (c and d)
a and b --> False as you suspect, but then (c and d) is evalued, and if c
succeeds also the expression d aka s[j+1].isalnum() which fails on accessing
s[j+1].
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