Recursion countup with string output

Question

I need to do a countup value that prints as a string -- so if the user would enter 5 it would count up from 1 -- ' 1 2 3 4 5' in a string and not seperate lines. This is what i have for a basic recursion function that counts up however it is not giving me the output of a string. Any help would be much appreciated

def countup(N, n=0):
    print(n)
    if n < N:
        countup(N, n + 1)

JohanC · Answer 1 · 2019-10-30T20:52:54.810

1

If you need to return a string, think about returning strings. The first part of your result is n converted to a string: str(n). While you're not yet done, you append a space followed by the countup of the rest of the numbers. Like so:

def countup(N, n=1):
    res = str(n)
    if n < N:
        res += ' ' + countup(N, n + 1)
    return res

print(countup(5))

Another version, without the need of a local variable, is:

def countup(N, n=1):
    if n < N:
        return str(n) + ' ' + countup(N, n + 1)
    else:
        return str(n)

edited Oct 30 '19 at 20:52

answered Oct 30 '19 at 20:43

JohanC

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can I ask what "res" means? – ellezi Oct 30 '19 at 20:48
`res` is a local variable with the temporary result. It's a string where you build up the result. – JohanC Oct 30 '19 at 20:50

score 1 · Answer 2 · answered Oct 30 '19 at 21:27

1

Why not just use str.join? No recursion needed here.

def countup(N, n=1):
    return ' '.join(map(str, range(n, N)))

answered Oct 30 '19 at 21:27

Jab

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Invoke Logic · Answer 3 · 2019-11-06T22:17:49.420

For start, this is a basically a duplicate of python recursive function that prints from 0 to n? and recursion, Python, countup, countdown

Change your ending of the print with print(n, end = ' ') to avoid the new line. See How to print without newline or space?

Also, your default argument should be n=1 to comply with it would count up from 1 assuming the call of countup(5)

def countup(N, n=1):
    print(n, end = ' ')
    if n < N:
        countup(N, n + 1)

Recursion countup with string output

3 Answers3