On 11/07/10 14:59, Dominik Danter wrote:
Hello
As en exercise I wrote the following function:
def recursfac(x,carryover=1):
print 'x:',x,'carryover:', carryover
if x > 1:
carryover *= x
recursfac(x-1, carryover)
else:
return carryover
print recursfac(3)
Very much to my surprise I get the following output:
x: 3 carryover: 1
x: 2 carryover: 3
x: 1 carryover: 6
None
Where did I go wrong?
Kind regards
Dominik Danter
I made a diagram to try to explain
recursfac(3)
recursfac(2, 3) <----|
recursfac(1, 6) _|
As you can see recursfac(1,6) returns it's value (carryover) to
recursfac(2, 3) which ignores it and completes it's execution ie
returning None to your original call which then prints out that return
value.
I hope that's clear.
Adam.
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