递归函数python，无法打印输出

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?

Answer 1

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)

Answer 2

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