On 2012-11-21 12:43, Giacomo Alzetta wrote:
I just came across this:
'spam'.find('', 5)
-1
Now, reading find's documentation:
print(str.find.__doc__)
S.find(sub [,start [,end]]) -> int
Return the lowest index in S where substring sub is found,
such that sub is contained within S[start:end]. Optional
arguments start and end are interpreted as in slice notation.
Return -1 on failure.
Now, the empty string is a substring of every string so how can find fail?
find, from the doc, should be generally be equivalent to
S[start:end].find(substring) + start, except if the substring is not found but
since the empty string is a substring of the empty string it should never fail.
[snip]
I think that returning -1 is correct (as far as returning -1 instead of
raising an exception like .index could be considered correct!) because
otherwise it whould be returning a non-existent index. For the string
"spam", the range is 0..4.
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