Answer to Question #333768 in Python for Jedy

Question

1. Copy the countdown function from Section 5.8 of your textbook.

def countdown(n):

if n <= 0:

print('Blastoff!')

else:

print(n)

countdown(n-1)

Write a new recursive function countup that expects a negative argument and counts “up” from that number. Output from running the function should look something like this:

>>> countup(-3)

-3

-2

-1

Blastoff!

Write a Python program that gets a number using keyboard input. (Remember to use input for Python 3 but raw_input for Python 2.)

If the number is positive, the program should call countdown. If the number is negative, the program should call countup. Choose for yourself which function to call (countdown or countup) for input of zero.

Provide the following.

The code of your program.

Output for the following input: a positive number, a negative number, and zero.

An explanation of your choice for what to call for input of zero.

Answer 1

def countdown(n):
    if n <= 0:
        print('Blastoff!')
    else:
        print(n)
        countdown(n - 1)


def countup(n):
    if n < 0:
        print(n)
        countup(n + 1)
    else:
        print('Blastoff!')


x = int(input())
countdown(x) if x >= 0 else countup(x)

OUTPUT:

Input number:5

5

4

3

2

1

Blastoff!

Input number:-5

-5

-4

-3

-2

-1

Blastoff!

Input number:0

Blastoff!

if input 0 --> call countdown(0)