python - calculate length of list recursively

Question

If you have a list = [1,2,3,4,5]

how would you recursively calculate the length of that list without using len(list)?

myarray = [1,2,3,4,5]

def mylist(myarray):
    if (myarray == []):
        print ("The list is empty")
        return 
    return 1 + ?

Don't want to use len but just add 1 each time there exists a value in list. How would I do that?

Answer 1

>>> def list_length(L):
...     if L:
...         return 1 + list_length(L[1:])
...     return 0
... 
>>> list_length(myarray)
5
>>> list_length([])
0
>>> list_length([1]*4)
4
>>> 

If the list has elements, return 1 + the length of the list minus one element.

You can do this a couple different ways, but slicing [:1] or [1:] will give you the elements minus the last or first respectively, makes sense.

If the list has no elements, return 0