Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python The Challenge

!= always fireing

here is my code so far:

import sys

player_names = []

add_player_to_list = input("Would you like to add a player to the list? Yes/No: ")
print(add_player_to_list)

if add_player_to_list.lower() != "yes" or "no":
    sys.exit("Sorry i dont understand")   

else:
    while add_player_to_list.lower() == "yes":
        player_name = input("Please enter the players name ")
        player_names.append(player_name)
        add_player_to_list = input("Would you like to add another player to the list? Yes/No: ")

if len(player_names) <= 1:
    sys.exit("There are not enough players to continue")

print("There are {} players in the team\nTeam Roster".format (len(player_names)))

player_index_number = 1

for player in player_names:
    print("Player {} : {}".format(player_index_number,player))
    player_index_number += 1

goalkeeper = int(input("Select a goalkeeper from the list by selecting the player number. (1-{})".format(len(player_names))))

goalkeeper_index = goalkeeper -1
print("The chosen goalkeeper is {} ".format(player_names[goalkeeper_index]))

Can anyone please explain to me why this part below thats at the top of my code is allways fireing even when i type yes or no as it is really confusing me:

if add_player_to_list.lower() != "yes" or "no": sys.exit("Sorry i dont understand")

1 Answer

Steven Parker
Steven Parker
217,456 Points

You can't use logic ("and" / "or") to combine terms, but you can use it to combine complete expressions:

if add_player_to_list.lower() != "yes" or "no":              # this won't do what you expect
if add_player_to_list.lower() != "yes" and add_player_to_list.lower() != "no":   # this will

Also, I think what you are calling "fireing" is more commonly referred to as "running".

Thanks, was wondering why it kept being triggered.

can you please tell me why the and command works but the or does not? i would of thought being either or would be the correct way to do this and the and would have to have both requirements met to be true....

Steven Parker
Steven Parker
217,456 Points

In logic, "and" requires both joined expressions to be true. But "or" only requires either expression to be true.

But mainly, you must always have complete expressions on both sides of the logic keyword. For example, add_player_to_list.lower() != "no" is a complete comparison expression, but just "no" is not.

right i got it working like this:

import sys

player_names = []

add_player_to_list = input("Would you like to add a player to the list? Yes/No: ")
print(add_player_to_list)

if add_player_to_list.lower() != "yes" and add_player_to_list.lower() != "no":
    sys.exit("Sorry i dont understand")
else:
    while add_player_to_list.lower() == "yes" and add_player_to_list.lower() != "no":
        player_name = input("Please enter the players name ")
        player_names.append(player_name)

        while add_player_to_list.lower() != "no":
            add_player_to_list = input("Would you like to add another player to the list? Yes/No: ")

            if add_player_to_list.lower() != "yes" and add_player_to_list.lower() != "no":
                print("Sorry mate i aint got a fkin clue what your onnabout")
                add_player_to_list = "yes"

            elif add_player_to_list.lower() == "yes":
                    player_name = input("Please enter the players name ")
                    player_names.append(player_name)

if len(player_names) <= 1: 
    sys.exit("There are not enough players to continue")

print("There are {} players in the team\nTeam Roster".format (len(player_names)))

player_index_number = 1
for player in player_names:
    print("Player {} : {}".format(player_index_number,player))
    player_index_number += 1

goalkeeper = int(input("Select a goalkeeper from the list by selecting the player number. (1-{})".format(len(player_names))))

goalkeeper_index = goalkeeper -1
print("The chosen goalkeeper is {} ".format(player_names[goalkeeper_index]))

Would this be the right way to do things as i have two loops going on at the same time...

Steven Parker
Steven Parker
217,456 Points

Making your code compact and efficient is a skill you will acquire with with experience and practice. One aspect of that is called the "DRY" principle, and will be covered in later courses. But making the code work will always be of primary importance.