[Tutor] exercise correct ??

[Sander Sweers]

On 6 September 2010 19:32, Roelof Wobben <rwobben at hotmail.com> wrote:
> def index_of(val, seq, start=0):
>     """
>       >>> index_of(9, [1, 7, 11, 9, 10])
>       3
>       >>> index_of(5, (1, 2, 4, 5, 6, 10, 5, 5))
>       3
>       >>> index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
>       6
>       >>> index_of('y', 'happy birthday')
>       4
>       >>> index_of('banana', ['apple', 'banana', 'cherry', 'date'])
>       1
>       >>> index_of(5, [2, 3, 4])
>       -1
>       >>> index_of('b', ['apple', 'banana', 'cherry', 'date'])
>       -1
>     """
>     plek = 0
>     if type(seq) == type([]):
>         plek = seq.index(val)
>     elif type(seq) == type(()):
>         seq = list (seq)
>         plek = seq.index(val)
>     else :
>         plek = seq.find(val)
>     return plek

Not sure if this is correct but why don't you check for the index
attribute? It is part of both lists and strings. Also you can use
try/except to catch a ValueError. My version below, but I dislike the
list() usage...

def index_of(val, seq, start=0):
    if hasattr(seq, 'index'):
        try:
            return seq.index(val, start)
        except ValueError:
            return -1
    else:
        try:
            return list(seq).index(val, start)
        except ValueError:
            return -1

> File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 70, in
> __main__.index_of
>
> Failed example:
>
> index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
>
> Expected:
>
> 6
>
> Got:
>
> 3
>
> But in that tuple 5 is on position 3.
>
> Is the exercise here wrong ?

Looks like it, or it's a typo.

Greets
Sander