This question already has answers here:
How to make program go back to the top of the code instead of closing [duplicate]
(7 answers)
Closed 8 years ago.
I've written a BMI calculator in python 3.4 and at the end I'd like to ask whether the user would like to use the calculator again and if yes go back to the beginning of the code. I've got this so far. Any help is very welcome :-)
#Asks if the user would like to use the calculator again
again =input("Thank you again for using this calculator, would you like to try again? Please type y for yes or n for no-")
while(again != "n") and (again != "y"):
again =input("Please type a valid response. Would you like to try again? Please type y for yes or n for no-")
if again == "n" :
print("Thank you, bye!")
elif again == "y" :
....
Wrap the whole code into a loop:
while True:
indenting every other line by 4 characters.
Whenever you want to "restart from the beginning", use statement
continue
Whenever you want to terminate the loop and proceed after it, use
break
If you want to terminate the whole program, import sys at the start of your code (before the while True: -- no use repeating the import!-) and whenever you want to terminate the program, use
sys.exit()
You just need to call the function if the user wants to start again:
def calculate():
# do work
return play_again()
def play_again():
while True:
again = input("Thank you again for using this calculator, would you like to try again? Please type y for yes or n for no-")
if again not in {"y","n"}:
print("please enter valid input")
elif again == "n":
return "Thank you, bye!"
elif again == "y":
# call function to start the calc again
return calculate()
calculate()
Related
This question already has answers here:
Asking the user for input until they give a valid response
(22 answers)
Closed 10 months ago.
I'm working on a Python project to get better with passing parameters into functions, so built a small program that takes user input and appends it to a list.
I've got most of that working, but I'm stuck on trying to allow a user to add another input if they want. The program asks if they'd like to add another input, with an if/else to handle a "Y" or "N" answer. That's working for the most part. The problem comes when a user enters an invalid response (anything other than a non-case sensitive 'y' or 'n'). At this point, the program is just displaying the goodbye message and ending. I think it has to do with my while loop, since it's supposed to break out when the new_input() function isn't resolving to true anymore. I want that function to continue to cycle through until the user enters a valid response, which would then cause it to continue and take another input or end appropriately.
Is there a way to get this to work with my combination of an if/else statement or is there another method that would work better? I'll drop the relevant pieces of the program below.
def new_input():
answer = input("Would you like to add more wisdom?(y/n): ")
if answer == "y" or answer == "Y":
return True
elif answer == 'n' or answer == 'N':
return False
else:
print("Invalid input. Please try again!")
def main():
name = input('Please enter your name:')
take_input(name)
while new_input():
take_input(name)
print_lib()
print("Thanks for your brain cells, buddy! Bye bye!")
Thanks for your help!
You can always return True, unless N/n is pressed, this way the program will continue running:
def new_input():
answer = input("Would you like to add more wisdom?(y/n): ")
if answer == "y" or answer == "Y":
return True
elif answer == 'n' or answer == 'N':
return False
else:
print("Invalid input. Please try again!")
return True
I am learning python and practicing my skills my making a simple text based adventure game.
In the game, I want to ask the player if they are ready to begin. I did this by creating a begin() function:
def begin():
print(raw_input("Are you ready to begin? > "))
while raw_input() != "yes":
if raw_input() == "yes":
break
print(start_adventure())
else:
print("Are you ready to begin? > ")
print(begin())
below this in my code is the function start_adventure()
def start_adventure():
print("Test, Test, Test")
When I run the program it starts up and I get to the point where it asks if I am ready to begin. Then it just loops infinitely and I can only exit the program if I completely close Powershell and restart Powershell. What am I doing wrong? How can I get the loop to stop once the player inputs "yes"?
What do you expect this to do? The solution to your problem is to try to understand what the code does, instead of just throwing stuff together. (Don't worry; at least 80% of us were at that stage at one point!)
As an aside, I strongly recommend using Python 3 instead of Python 2; they made a new version of Python because Python 2 was full of really strange, confusing stuff like input causing security vulnerabilities and 10 / 4 equalling 2.
What do you want this to do?
Repeatedly ask the user whether they are ready to begin until they answer "yes".
Call start_adventure().
Ok. Let's put what we've got so far into a function:
def begin():
while something:
raw_input("Are you ready to begin? > ")
start_adventure()
There are a lot of gaps in here, but it's a start. Currently, we're getting the user's input and throwing it away, because we're not storing it anywhere. Let's fix that.
def begin():
while something:
answer = raw_input("Are you ready to begin? > ")
start_adventure()
This is starting to take shape. We only want to keep looping while answer != "yes"...
def begin():
while answer != "yes":
answer = raw_input("Are you ready to begin? > ")
start_adventure()
Hooray! Let's see if this works!
Traceback (most recent call last):
File "example", line 2, in <module>
while answer != "yes":
NameError: name 'answer' is not defined
Hmm... We haven't set a value for answer yet. In order to make the loop run, it has to be something that isn't equal to "yes". Let's go with "no":
def begin():
answer = "no"
while answer != "yes":
answer = raw_input("Are you ready to begin? > ")
start_adventure()
This will work!
Python 3 Solution
You should not be calling raw_input() multiple times. Simply instantiate x and then wait until the user inputs Y to call your start_adventure function. This should get you started:
def start_adventure():
print('We have started!')
#do something here
def begin():
x = None
while x!='Y':
x = input('Are you ready to begin (Y/N)?')
if x=='Y':
start_adventure()
begin()
Your Raw input function (I'm assuming it works correctly) is never assigned to a variable. Instead you call it in your print statement, print the result of it and then you call it again in your while loop condition.
You never actually satisfy the while loop condition because your input isn't assigned to a variable. Assign Raw_input("Are you ready to begin? >") to a variable to store the input. Then while loop with the variable. Make sure in your while loop when the condition is met you reset the variable to something else.
Your program flow is wrong too, you need to call your raw input function inside the while loop. This will change the while loop condition so that when the condition is met (user types "yes") it won't loop infinitely. Hope this helps!
Example of what you need in code form:
//initialize the condition to no value
condition = None;
#check the condition
while condition != "yes"
#change the condition here based on user input **inside the loop**
condition = raw_input("are you ready to begin? >")
if condition == "yes":
#condition is met do what you need
else:
#condition not met loop again
#nothing needs to go here to print the message again
This question already has an answer here:
print statement inside of input returns with a "none"
(1 answer)
Closed 6 years ago.
I am writing a game using loops and I haven't defined any functions in my code, but only using basic ones like print(). My code itself does exactly what it's supposed to do, but it throws in a None where the user is supposed to give input to the code.
while loca == 22:
if (lever=="back") and (dial=="red"):
print("congratlations! You have won the game!")
play=input(print("Would you like to play again? Type 'Y' for yes and 'N' for no."))
while play in ["yes","y","Y","Yes"]:
loca = 1
play="reset"
while play in ["no","n","N","No"]:
print("Thanks for playing!")
quit()
while (not play == "reset"):
while (not play == ["no","n","N","No"]) and (not play == ["yes","y","Y","Yes"]):
play=input(print("Sorry, I didn't understand. Please enter 'Y' for yes, or 'N' for no."))
else:
print("Hmm.. You don't quite have the right combination yet!")
I know the quit() is a function, but I also tried the code with it removed and it still returned a None. I have never had this problem with other programs I wrote that used the same function I am using in this code.
For this assignment, we are supposed to implement the quit function into the code, or some variation of it but we haven't learned about a return for functions (this code isn't supposed to have any author defined functions) and it seems that the only answer I can find online is to do with a return. I thought I would try my luck here and maybe it is just something small that I am missing.
The print function returns None, which you're then passing to input, remove the calls to print, since input already takes care of printing the string passed.
Instead of:
play=input(print("Would you like to play again? Type 'Y' for yes and 'N' for no."))
Use:
play=input("Would you like to play again? Type 'Y' for yes and 'N' for no.")
The line where you create the variable play. You misuse the input function the prompt you write in the function already is displayed for the user. However by putting in print() you return none.
That line should be:
play = input("Would you like to play again? Type 'Y' for yes and 'N' for no.")
P.S. you should try and conform to the PEP 8 - python style guide
I have been trying to convert some code into a try statement but I can't seem to get anything working.
Here is my code in pseudo code:
start
run function
check for user input ('Would you like to test another variable? (y/n) ')
if: yes ('y') restart from top
elif: no ('n') exit program (loop is at end of program)
else: return an error saying that the input is invalid.
And here is my code (which works) in python 3.4
run = True
while run == True:
spuriousCorrelate(directory)
cont = True
while cont == True:
choice = input('Would you like to test another variable? (y/n) ')
if choice == 'y':
cont = False
elif choice == 'n':
run = False
cont = False
else:
print('This is not a valid answer please try again.')
run = True
cont = True
Now what is the proper way for me to convert this into a try statement or to neaten my code somewhat?
This isn't a copy of the mentioned referenced post as I am trying to manage two nested statements rather than only get the correct answer.
If you want to make your code neater, you should consider having
while run:
instead of
while run == True:
and also remove the last two lines, because setting run and cont to True again isn't necessary (their value didn't change).
Furthermore, I think that a try - except block would be useful in the case of an integer input, for example:
num = input("Please enter an integer: ")
try:
num = int(num)
except ValueError:
print("Error,", num, "is not a number.")
In your case though I think it's better to stick with if - elif - else blocks.
Ok so as a general case I will try to avoid try...except blocks
Don't do this. Use the right tool for the job.
Use raise to signal that your code can't (or shouldn't) deal with the scenario.
Use try-except to process that signal.
Now what is the proper way for me to convert this into a try statement?
Don't convert.
You don't have anything that raises in your code, so there is no point of try-except.
What is the proper way to neaten my code somewhat?
Get rid of your flag variables (run, cont). You have break, use it!
This is prefered way of imlementing do-while, as Python docs says; unfortunately, I cannot find it to link it right now.
If someone finds it, feel free to edit my answer to include it.
def main()
while True: # while user wants to test variables
spuriousCorrelate(directory) # or whatever your program is doing
while True: # while not received valid answer
choice = input('Would you like to test another variable? (y/n) ')
if choice == 'y':
break # let's test next variable
elif choice == 'n':
return # no more testing, exit whole program
else:
print('This is not a valid answer please try again.')
This question already has an answer here:
Python function NameError [duplicate]
(1 answer)
Closed 3 years ago.
So I have this game:
import sys
def Start():
print("Hello and welcome to my first Python game. I made it for fun and because I am pretty bored right now.")
print("I hope you enjoy my EPIC TEXT GAME")
play = input("do you want to play? (Y / N) ")
if play == "Y":
game()
if play == "N":
sys.exit()
def game():
print("That's pretty much what I've done so far! :P -- yea yea, it's nothing -- IT IS!. Bye now")
input("Press enter to exit")
If I type "Y" I want to go to game(). It doesn't.
You have defined game after you tried and use it. You need to define functions, variables, etc. before you use them.
Also, your code only matched on upper case Y and not lower case y. To make all input upper case, you should use the .upper() method on it
Change the code to:
def game():
print("That's pretty much what I've done so far!")
input("Press enter to exit")
if play.upper() == "Y":
game()
elif play.upper() == "N":
sys.exit()
It is usually best form to not have any global code, and instead include it in a main function if the python code is being run as the main. You can do this by using:
if __name__ == "__main__":
Start()
And then put all that global code into the Start method.
Again, make sure you declare before you use.
You're using the input() function which executes the input as a command immediately after reading it from stdin.
You probably want to use raw_input() which will simply return what the user entered