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Python The Challenge

Posted by james viggers
james viggers
1,397 Points

!= 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
231,269 Points
Steven Parker
Steven Parker
231,269 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".

james viggers
james viggers
1,397 Points

Thanks, was wondering why it kept being triggered.

james viggers
james viggers
1,397 Points

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
231,269 Points
Steven Parker
Steven Parker
231,269 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.

james viggers
james viggers
1,397 Points

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
231,269 Points
Steven Parker
Steven Parker
231,269 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.