Recursive function python, cannot print an output

Question

I have just started to program in python, and I am stuck with a problem regarding recursion.

The program seems to compile, however, the print output is not shown.

Here is the program:

print 'type s word'
s = raw_input()
print 'enter a number'
n = raw_input()

def print_n(s, n):

 if n<=0:
  return 
 print s
 print_n(s, n-1)

the output i get is:

xxxx@xxxx-Satellite-L600:~/Desktop$ python 5exp3.py
type s string
hello
add the number of recursions
4
xxxx@xxxx-Satellite-L600:~/Desktop$

What is wrong, and how can I get the program to show an output?

I recommend using more than one space for your indentation level. — Waleed Khan
– Waleed Khan, Commented Oct 31, 2012 at 20:16
The code you show doesn't actually call the recursive function... if it did you would get an exception as raw_input returns strings which you must convert to integers with int. — l4mpi
– l4mpi, Commented Oct 31, 2012 at 20:17
You should also use return print_n(s, n-1), when calling the function recursively, though it might not cause any problem in this case, but keep that in mind for future uses. — Ashwini Chaudhary
– Ashwini Chaudhary, Commented Oct 31, 2012 at 20:23
@StevenRumbalski yes I mentioned that, I just wanted to tell the OP that it can be useful when he's returning values from function, instead of just printing, coz in that case the function will return None. — Ashwini Chaudhary
– Ashwini Chaudhary, Commented Oct 31, 2012 at 20:56

Steven Rumbalski · Accepted Answer · 2012-10-31 20:46:11Z

5

Your posted code defines the function print_n but never calls it. After the function definition place a print_n(s, n).

Once you do this you'll find some errors caused by the fact the n is currently a string (raw_input returns a string). Use int(a_string) to convert a string to an integer. Calling your function like this will solve the issue

print_n(s, int(n))

Or do

n = int(raw_input())

The complete code:

s = raw_input('type a word: ')
n = int(raw_input('enter a number: '))

def print_n(s, n):
    if n <= 0:
        return 
    print s
    print_n(s, n-1)

print_n(s, n)

edited Oct 31, 2012 at 20:46

answered Oct 31, 2012 at 20:23

Steven Rumbalski

45.8k10 gold badges96 silver badges125 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

gefei · Accepted Answer · 2012-10-31 20:17:11Z

2

try n = raw_input() -> n = int(raw_input())

answered Oct 31, 2012 at 20:17

gefei

20k9 gold badges54 silver badges71 bronze badges

1 Comment

Steven Rumbalski Over a year ago

You are correct that n needs to be an integer, but the initial issue is that he never calls the print_n. Otherwise, he would have received TypeError on the first recursion. (It would not have exited early because "string" <= 0" evaluates to False in Python 2).

Collectives™ on Stack Overflow

Recursive function python, cannot print an output

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related