Question

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

Answer:

Complete Python code along with step by step explanation is provided below.

Python Code:

# create a recursive countdown function that will count in decreasing order

def countdown(n):

   if n >= 0:

       print(n)

       countdown(n-1)

# create a recursive countup function that will count in increasing order.

def countup(n):

   if n <= 0:

       print(n)

       countup(n+1)  

# driver code

def main():

# get input from the user

   n = int(input("Please enter any number: "))

# call the countdown function if input n is zero or greater than zero.

# whether you choose countdown or countup for input n the outcome will be same in both cases

   if n >= 0:

       countdown(n)

# call the countup function for the remaining case that is n is less than zero.

   else:

       countup(n)

# call the main function

main()

Output:

Test 1:

Please enter any number: 5

5

4

3

2

1

0

Test 2:

Please enter any number: -6

-6

-5

-4

-3

-2

-1

0

Test 3:

Please enter any number: 0

0

Answer 2

Following  are the python program to the given question:

Program Explanation:

• Defining two methods "countdown, countup" that takes one parameter.
• In both methods, it uses an if block that checks the parameter value and prints its value with the message.
• In the next step, the "n" variable is defined that inputs the value and uses the if block that checks the value and calls the above method accordingly.

Program:

def countdown(n):#defining a method

   if n <= 0:#defining an if block that checks n value less than equal to 0

       print('Blastoff!')#print message

   else:#defining else block  

       print(n)#print number value

       countdown(n - 1)#calling method countdown

def countup(n):#defining countup method that takes one parameter

   if n >= 0:#defining if block that checks parameter value greater than equal to 0

       print('Blastoff!')#print message

   else:#defining else block

       print(n)#print the parameter value

       countup(n + 1)#Calling method countup

n = int(input("Enter an integer: "))   #defining n variable that inputs value

if n < 0:#defining if block that check n value less than 0

   countup(n)#Calling countup method

else:#defining else block  

   countdown(n)#Calling countdown method

Output:

Please find the attached file.

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