This question already has answers here:
error in python d not defined. [duplicate]
(3 answers)
Closed 8 years ago.
def money():
cashin = input("Please insert money: £1 Per Play!")
dif = 1 - cashin
if cashin < 1.0:
print ("You have inserted £", cashin, " you must insert another £", math.fabs(dif))
elif cashin > 1.0:
print ("Please take your change: £", math.fabs(dif))
else:
print ("You have inserted £1")
menu()
def menu():
print ("Please choose an ARTIST: <enter character ID>")
print ("<BEA> - The Beatles")
print ("<MIC> - Michael Jackson")
print ("<BOB> - Bob Marley")
cid = input()
if cid.upper == ("BEA"):
correct = input("You have selected the Beatles, is this correct? [Y/N]:")
if correct.upper() == ("Y"):
bea1()
else:
menu()
elif cid.upper() == ("MIC"):
correct = input("You have selected Michael Jackson, is this correct? [Y/N]:")
if correct.upper() == ("Y"):
mic1()
else:
menu()
elif cid.upper() == ("BOB"):
correct = input("You have selected Bob Marley, is this correct? [Y/N]:")
if correct.upper() == ("Y"):
bob1()
else:
menu()
else:
print ("That is an invalid character ID")
menu()
this is part of my code for a jukebox
my code is giving me the error that bea is not defined if I type 'bea' on the 'CHOOSE AN ARTIST' input. but i'm not trying to use it as a function or a variable? I want to use an if statement to decide what to do based on the users input
usually this works for me, I don't know what the problem is. This is only a section of my code, if you need to see more let me know
In Python 2.x, to get a string from a prompt, you use raw_input() instead of input():
cid = raw_input()
The input function in Python 2 is not equivalent to input in Python 3. It does not return a string, but evaluates it. In your case, you type bea and it tries to evalueate bea as an expression. But this name is not defined.
As mentioned in the docs for input:
Equivalent to eval(raw_input(prompt)).
Also, as #frostnational notes in his comment, you forgot to actually call the upper method on the next line, so you are trying to compare the method itself with a string. You want
if cid.upper() == "BEA":
Related
I am attempting to make a game that I made via Rpg Maker MV in python but I've hit a road block in the if statement or rather the gender input. The code is meant to have the user input either "Boy" or "Girl" and depending on that the variable "gender" will be set for pronouns. How ever the console is saying This
This is the code
import time
print ("Elvoria")
print ("Start")
input = input()
if input == ("Start"):
print ("Always Great To See New People")
time.sleep(1)
print ("Now Are You A Boy Or Girl")
genderin = input()
if input == ("Boy"):
gender = 1
elif input == ("Girl"):
gender = 2
else:
print ("Error")
You need to check the input using the variable name genderin that you defined, instead of input == ("Boy").
EDIT: Also, you are mirroring the built-in method input() with the variable name input and you should not do that. Rename your variable to e.g. start_input.
import time
print ("Elvoria")
print ("Start")
start_input = input()
if start_input == "Start":
print ("Always Great To See New People")
time.sleep(1)
print ("Now Are You A Boy Or Girl")
genderin = input()
if genderin == "Boy":
gender = 1
elif genderin == "Girl":
gender = 2
else:
print ("Error")
You're defining the variable "input" on line 4 to be a string, given from the "input" function. This overrides the keyword. Then, on line 9, you're calling "input" again. Since you've replaced the built-in function with a string, an error is thrown (the error "not callable" means that you're trying to treat a non-function like a function).
Here's your code sample, without overriding built-in methods:
import time
print ("Elvoria")
print ("Start")
user_input = input()
if user_input == ("Start"):
print ("Always Great To See New People")
time.sleep(1)
print ("Now Are You A Boy Or Girl")
genderin = input()
if genderin == ("Boy"):
gender = 1
elif genderin == ("Girl"):
gender = 2
else:
print ("Error")
You should avoid using input as a varible name, since a built-in function with that name already exists, input(). So just change it's name to something else. Secondly, you're storing the gender input (boy/girl) in genderin, but then checking input, when you should be checking genderin. So the code after fixing these would look something like this:
import time
print ("Elvoria")
print ("Start")
choice = input()
if choice == "Start":
print("Always Great To See New People")
time.sleep(1)
print("Now Are You A Boy Or Girl?")
genderin = input()
if genderin == "Boy":
gender = 1
elif genderin == "Girl":
gender = 2
else:
print("Error")
I have used choice for demonstration purposes, you can use a different name if you want, just remember to make sure that a python built-in with that name doesn't exist. Also, no need to put ("Start") in the if statement, use "Start" instead (same goes for other if/elif statements)
You have also used print ("example") (space between print and brackets), i've rarely ever seen someone using this, most people use print("example") instead.
Finally a tip -> You can make the string lowercase, genderin = genderin.lower() to manage case sensitivity, i.e, both boy and Boy will be valid inputs, etc.
I'm trying to create a menu for my application, the menu has 4 options and each of these options should return with the correct information when the user has entered the chosen value. i keep getting an error with the Elif statements.
I am a newbie so please understand where am coming from.
much appreciation.
when i indent the while ans: i will receive an error says invalid syntax after indenting the elif ans==2.
elif ans==2 <--- this error keeps saying indention block error or syntex invalid when i indent it.
def print_menu(self,car):
print ("1.Search by platenumber")
print ("2.Search by price ")
print ("3.Delete 3")
print ("4.Exit 4")
loop=True
while loop:
print_menu()
ans==input("Please choose from the list")
if ans==1:
print("These are the cars within this platenumber")
return platenumber_
while ans:
if ans==2:
elif ans==2:
print("These are the prices of the cars")
return price_
elif ans==3:
print("Delete the cars ")
return delete_
elif ans==4:
return Exit_
loop=False
else:
raw_input("please choose a correct option")
You have a while loop without a body. Generally speaking, if there is an indentation error message and the error is not on the line mentioned, it's something closely above it.
loop=True
while loop:
print_menu()
ans = int(input("Please choose from the list"))
if ans==1:
print("These are the cars within this platenumber")
# return some valid information about plate numbers
elif ans==2:
print("These are the prices of the cars")
# return some valid information about pricing
elif ans==3:
print("Delete the cars ")
# Perform car deletion action and return
elif ans==4:
# I am assuming this is the exit option? in which case
# return without doing anything
else:
# In this case they have not chosen a valid option. Send
# A message to the user, and do nothing. The while loop will run again.
print("please choose a correct option")
Also, your code is a bit confusing to me. It looks like you're going to return car_ no matter what, which means your loop will only execute once. Also, = is assignment and == is equality. Be careful.
I am a programming beginner and I am trying to build a fill-in-the-blank quiz. I am almost finished but I am stuck on 2 problems I am not able to solve, whatever I do. I would really appreciate your help with this. Thank you for helping me with this!
If you try to run the code and play the game:
1) It prints the quiz according to the difficulty(easy-insane) and quiz you want to play(apple, bond and programming quiz) which is great but afterwards it prompts you to choose difficulty again (the player_level() function keeps going even though the player/user has already chosen the difficulty level. I don't really understand why it does it? The player_level() procedure seems perfectly okay and logical to me.
2) The errors:
a) local variable blanks_index referenced before assignment
b) global name list_of_answers is not defined.
I know that it is related to the initialize_game() function but I don't know how to change the code so it refers all the variables (blanks_index, answers_index, player_lives) correctly.
It could be solved by creating global variables(I guess) but that is not a good practice so I am trying to avoid it. Formerly, the whole function initialise_game() and play_game() were one function, but as there are over 25 lines of code in one function, it is not a good practice as it is long and messy and I know that I can separate it but I don't know how.
Here is the code:
"""3 diffferent quizzes : Apple quiz, James Bond quiz, Programming quiz"""
"""Quiz and answers about Apple"""
Apple_quiz = ("The most valuable company in terms of market cap in 2016 is, ___1___."
"It was founded in ___2___. Its flagship product is called ___3___."
"___1___ has many competitors, the biggest rival is ___4___,founded by"
" nobody but the richest man on the planet,___5___ ___6___.")
list_of_answers_Apple = ["Apple", "1976", "Iphone", "Microsoft", "Bill", "Gates"]
"""Quiz and answers about Bond"""
Bond_quiz = ("James Bond is agent ___1___. He serves his country,___2___ ___3___"
" against its enemies. His car of choice is usually ___4___ ___5___."
" His favorite drink is ___6___.")
list_of_answers_Bond = ["007", "United", "Kingdom", "Aston", "Martin", "Martini"]
"""Quiz and answers about programming basics"""
Programming_quiz = ("___1___ are created with the def keyword. ___1___ are also called ___2___"
" You specify the inputs a ___1___ take by adding ___3___ separated by commas"
" between the parentheses. ___3___ can be standard data types such as string, number"
" ,dictionary, tuple, and ___4___ or can be more complicated such as ___5___"
" and ___6___ functions.")
list_of_answers_Programming = ["Functions", "procedures", "arguments", "lists", "objects", "lambda"]
blank_space = ["___1___", "___2___", "___3___", "___4___", "___5___", "___6___]"]
#List of levels with corresponding lives/guesses that player can have
quiz_list = ["Apple", "Bond", "Programming"]
level_list = ["easy", "medium", "hard", "superhard", "insane"]
lives_easy = 5
lives_medium = 4
lives_hard = 3
lives_superhard = 2
lives_insane = 1
def choose_quiz():
""" Prompts player to pick a type of quiz and loads the quiz """
#Input = player_quiz (raw input from player)
#Output = loaded quiz, player chose
while True:
player_quiz = raw_input("Please, select a quiz you want to play: "
"(Apple, Bond or Programming): ")
if player_quiz == "Apple":
return Apple_quiz
elif player_quiz == "Bond":
return Bond_quiz
elif player_quiz == "Programming":
return Programming_quiz
else:
print "We don't have such quiz, pick again!"
def answers_for_quiz():
""" Loads appropiate answers to the quiz that player has chosen"""
#Input = player quiz (raw input from player)
#Output = loaded quiz answers from the quiz player chose
player_quiz_pick = choose_quiz()
if player_quiz_pick == Apple_quiz:
return list_of_answers_Apple
elif player_quiz_pick == Bond_quiz:
return list_of_answers_Bond
elif player_quiz_pick == Programming_quiz:
return list_of_answers_Programming
def player_level():
""" Loads a difficulty that player chooses """
#Input = player_level_input (raw input of player choosing a difficulty)
#Output = corresponding number of lives:
#Easy = 5 lives, Medium = 4 lives
#Hard = 3 lives, Superhard = 2 lives
#Insane = 1 life
while True:
player_level_input = raw_input("Please type in a difficulty level: "
"(easy, medium, hard, superhard, insane): ")
if player_level_input == "easy":
return lives_easy #Easy = 5 lives
elif player_level_input == "medium":
return lives_medium #Medium = 4 lives
elif player_level_input == "hard":
return lives_hard #Hard = 3 lives
elif player_level_input == "superhard":
return lives_superhard #Superhard = 2 lives
elif player_level_input == "insane":
return lives_insane #Insane = 1 life
else:
print "We do not have such difficulty! Pick again!"
def correct_answer(player_answer, list_of_answers, answers_index):
""" Checks, whether the the answer from player matches with the answer list. """
#Input: player_answer (raw input that player enters in order to fill in the blank)
#Output: "Right answer!" or "Wrong! Try again!" this output will be later used in the game
if player_answer == list_of_answers[answers_index]:
return "Right answer!"
return "Wrong! Try again!"
def initialize_game():
"""Functions that sets up a game so we can play it """
player_quiz_pick, player_level_pick, list_of_answers = choose_quiz(), player_level(), answers_for_quiz()
print player_quiz_pick
print "\nYou will get maximum " + str(player_level_pick) + " guesses for this game. Good luck.\n"
blanks_index, answers_index, player_lives = 0, 0, 0
#for elements in blank_space:
while blanks_index < len(blank_space):
player_answer = raw_input("Please type in your answer for " + blank_space[blanks_index] + ": ")
if correct_answer(player_answer,list_of_answers,answers_index) == "Right answer!":
print "Correct answer! Keep going!\n"
player_quiz_pick = player_quiz_pick.replace(blank_space[blanks_index],player_answer)
answers_index += 1
blanks_index += 1
print player_quiz_pick
if blanks_index == len(blank_space):
print "Congratulations! You nailed it! You are the winner!"
else:
player_level_pick -= 1
if player_level_pick == 0:
print "Game over! Maybe next time!"
break
else:
print "One life less, that sucks! Have another shot!"
print "You have " + str(player_level_pick) + " guesses left."
initialize_game()
Your main problem is that you keep calling the same functions over and over again and do not save the input into variables. Here are some tips about your code and questions:
You are not doing anything with your player_level() method call, so the player doesn't actually chooses a level in a way that affects the game. You should change the function call, so the returned value will be stored.
//the call to the method:
player_level_pick = player_level()
Afterwards, you keep calling the player_level() method, and not using the actual answer that the user supplied. Change all player_level() appearences to player_level_pick - the variable you use to save the answer (as I showed above). Same goes to all other unneeded function calls such as choose_level().
You should initialize number_of_guesses, player_lives, list_of_answers, and other vars to a matching value to player_level_pick as well, so it will hold the right value according to the level. Likewise, you should change this line:
# the line that checks if game is over
# change from:
if number_of_guesses == player_lives:
# to :
if number_of_guesses == 0:
In order to return multiple values, you have to use tuples. Using multiple return statements one after the other does not work anywhere.
so, instead of:
return list_of_answers
return number_of_guesses
return blanks_index
return answers_index
return player_lives
you should use tuples, and unpack them properly:
# the return statement:
return (list_of_answers, number_of_guesses, blanks_index, answers_index, player_lives)
# and the unpacking in the calling function:
list_of_answers, number_of_guesses, blanks_index, answers_index, player_lives = initialize_game()
this way, all of the returned values go into the wanted variables in the calling function. this way, you need to call the initialize_game() from play_game(). it will be the efficient way for you.
Just saying it again, as I said in the end of (4) - you should unit initialize_game() and play_game() into a single function (because a lot of data is the same needed data), or just call initialize_game() from play_game().
Better practice then using this recursivly: return choose_level(), you should use a while True: loop, and just brake when you get a proper answer.
This question already has answers here:
Asking the user for input until they give a valid response
(22 answers)
Closed 6 years ago.
I'm trying to figure out how to make Python go back to the top of the code. In SmallBasic, you do
start:
textwindow.writeline("Poo")
goto start
But I can't figure out how you do that in Python :/ Any ideas anyone?
The code I'm trying to loop is this
#Alan's Toolkit for conversions
def start() :
print ("Welcome to the converter toolkit made by Alan.")
op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")
if op == "1":
f1 = input ("Please enter your fahrenheit temperature: ")
f1 = int(f1)
a1 = (f1 - 32) / 1.8
a1 = str(a1)
print (a1+" celsius")
elif op == "2":
m1 = input ("Please input your the amount of meters you wish to convert: ")
m1 = int(m1)
m2 = (m1 * 100)
m2 = str(m2)
print (m2+" m")
if op == "3":
mb1 = input ("Please input the amount of megabytes you want to convert")
mb1 = int(mb1)
mb2 = (mb1 / 1024)
mb3 = (mb2 / 1024)
mb3 = str(mb3)
print (mb3+" GB")
else:
print ("Sorry, that was an invalid command!")
start()
So basically, when the user finishes their conversion, I want it to loop back to the top. I still can't put your loop examples into practise with this, as each time I use the def function to loop, it says that "op" is not defined.
Use an infinite loop:
while True:
print('Hello world!')
This certainly can apply to your start() function as well; you can exit the loop with either break, or use return to exit the function altogether, which also terminates the loop:
def start():
print ("Welcome to the converter toolkit made by Alan.")
while True:
op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")
if op == "1":
f1 = input ("Please enter your fahrenheit temperature: ")
f1 = int(f1)
a1 = (f1 - 32) / 1.8
a1 = str(a1)
print (a1+" celsius")
elif op == "2":
m1 = input ("Please input your the amount of meters you wish to convert: ")
m1 = int(m1)
m2 = (m1 * 100)
m2 = str(m2)
print (m2+" m")
if op == "3":
mb1 = input ("Please input the amount of megabytes you want to convert")
mb1 = int(mb1)
mb2 = (mb1 / 1024)
mb3 = (mb2 / 1024)
mb3 = str(mb3)
print (mb3+" GB")
else:
print ("Sorry, that was an invalid command!")
If you were to add an option to quit as well, that could be:
if op.lower() in {'q', 'quit', 'e', 'exit'}:
print("Goodbye!")
return
for example.
Python, like most modern programming languages, does not support "goto". Instead, you must use control functions. There are essentially two ways to do this.
1. Loops
An example of how you could do exactly what your SmallBasic example does is as follows:
while True :
print "Poo"
It's that simple.
2. Recursion
def the_func() :
print "Poo"
the_func()
the_func()
Note on Recursion: Only do this if you have a specific number of times you want to go back to the beginning (in which case add a case when the recursion should stop). It is a bad idea to do an infinite recursion like I define above, because you will eventually run out of memory!
Edited to Answer Question More Specifically
#Alan's Toolkit for conversions
invalid_input = True
def start() :
print ("Welcome to the converter toolkit made by Alan.")
op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")
if op == "1":
#stuff
invalid_input = False # Set to False because input was valid
elif op == "2":
#stuff
invalid_input = False # Set to False because input was valid
elif op == "3": # you still have this as "if"; I would recommend keeping it as elif
#stuff
invalid_input = False # Set to False because input was valid
else:
print ("Sorry, that was an invalid command!")
while invalid_input: # this will loop until invalid_input is set to be False
start()
You can easily do it with loops, there are two types of loops
For Loops:
for i in range(0,5):
print 'Hello World'
While Loops:
count = 1
while count <= 5:
print 'Hello World'
count += 1
Each of these loops print "Hello World" five times
Python has control flow statements instead of goto statements. One implementation of control flow is Python's while loop. You can give it a boolean condition (boolean values are either True or False in Python), and the loop will execute repeatedly until that condition becomes false. If you want to loop forever, all you have to do is start an infinite loop.
Be careful if you decide to run the following example code. Press Control+C in your shell while it is running if you ever want to kill the process. Note that the process must be in the foreground for this to work.
while True:
# do stuff here
pass
The line # do stuff here is just a comment. It doesn't execute anything. pass is just a placeholder in python that basically says "Hi, I'm a line of code, but skip me because I don't do anything."
Now let's say you want to repeatedly ask the user for input forever and ever, and only exit the program if the user inputs the character 'q' for quit.
You could do something like this:
while True:
cmd = raw_input('Do you want to quit? Enter \'q\'!')
if cmd == 'q':
break
cmd will just store whatever the user inputs (the user will be prompted to type something and hit enter). If cmd stores just the letter 'q', the code will forcefully break out of its enclosing loop. The break statement lets you escape any kind of loop. Even an infinite one! It is extremely useful to learn if you ever want to program user applications which often run on infinite loops. If the user does not type exactly the letter 'q', the user will just be prompted repeatedly and infinitely until the process is forcefully killed or the user decides that he's had enough of this annoying program and just wants to quit.
write a for or while loop and put all of your code inside of it? Goto type programming is a thing of the past.
https://wiki.python.org/moin/ForLoop
You need to use a while loop. If you make a while loop, and there's no instruction after the loop, it'll become an infinite loop,and won't stop until you manually stop it.
def start():
Offset = 5
def getMode():
while True:
print('Do you wish to encrypt or decrypt a message?')
mode = input().lower()
if mode in 'encrypt e decrypt d'.split():
return mode
else:
print('Please be sensible try just the lower case')
def getMessage():
print('Enter your message wanted to :')
return input()
def getKey():
key = 0
while True:
print('Enter the key number (1-%s)' % (Offset))
key = int(input())
if (key >= 1 and key <= Offset):
return key
def getTranslatedMessage(mode, message, key):
if mode[0] == 'd':
key = -key
translated = ''
for symbol in message:
if symbol.isalpha():
num = ord(symbol)
num += key
if symbol.isupper():
if num > ord('Z'):
num -= 26
elif num < ord('A'):
num += 26
elif symbol.islower():
if num > ord('z'):
num -= 26
elif num < ord('a'):
num += 26
translated += chr(num)
else:
translated += symbol
return translated
mode = getMode()
message = getMessage()
key = getKey()
print('Your translated text is:')
print(getTranslatedMessage(mode, message, key))
if op.lower() in {'q', 'quit', 'e', 'exit'}:
print("Goodbye!")
return
This question already has answers here:
Asking the user for input until they give a valid response
(22 answers)
Closed 6 years ago.
I'm trying to figure out how to make Python go back to the top of the code. In SmallBasic, you do
start:
textwindow.writeline("Poo")
goto start
But I can't figure out how you do that in Python :/ Any ideas anyone?
The code I'm trying to loop is this
#Alan's Toolkit for conversions
def start() :
print ("Welcome to the converter toolkit made by Alan.")
op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")
if op == "1":
f1 = input ("Please enter your fahrenheit temperature: ")
f1 = int(f1)
a1 = (f1 - 32) / 1.8
a1 = str(a1)
print (a1+" celsius")
elif op == "2":
m1 = input ("Please input your the amount of meters you wish to convert: ")
m1 = int(m1)
m2 = (m1 * 100)
m2 = str(m2)
print (m2+" m")
if op == "3":
mb1 = input ("Please input the amount of megabytes you want to convert")
mb1 = int(mb1)
mb2 = (mb1 / 1024)
mb3 = (mb2 / 1024)
mb3 = str(mb3)
print (mb3+" GB")
else:
print ("Sorry, that was an invalid command!")
start()
So basically, when the user finishes their conversion, I want it to loop back to the top. I still can't put your loop examples into practise with this, as each time I use the def function to loop, it says that "op" is not defined.
Use an infinite loop:
while True:
print('Hello world!')
This certainly can apply to your start() function as well; you can exit the loop with either break, or use return to exit the function altogether, which also terminates the loop:
def start():
print ("Welcome to the converter toolkit made by Alan.")
while True:
op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")
if op == "1":
f1 = input ("Please enter your fahrenheit temperature: ")
f1 = int(f1)
a1 = (f1 - 32) / 1.8
a1 = str(a1)
print (a1+" celsius")
elif op == "2":
m1 = input ("Please input your the amount of meters you wish to convert: ")
m1 = int(m1)
m2 = (m1 * 100)
m2 = str(m2)
print (m2+" m")
if op == "3":
mb1 = input ("Please input the amount of megabytes you want to convert")
mb1 = int(mb1)
mb2 = (mb1 / 1024)
mb3 = (mb2 / 1024)
mb3 = str(mb3)
print (mb3+" GB")
else:
print ("Sorry, that was an invalid command!")
If you were to add an option to quit as well, that could be:
if op.lower() in {'q', 'quit', 'e', 'exit'}:
print("Goodbye!")
return
for example.
Python, like most modern programming languages, does not support "goto". Instead, you must use control functions. There are essentially two ways to do this.
1. Loops
An example of how you could do exactly what your SmallBasic example does is as follows:
while True :
print "Poo"
It's that simple.
2. Recursion
def the_func() :
print "Poo"
the_func()
the_func()
Note on Recursion: Only do this if you have a specific number of times you want to go back to the beginning (in which case add a case when the recursion should stop). It is a bad idea to do an infinite recursion like I define above, because you will eventually run out of memory!
Edited to Answer Question More Specifically
#Alan's Toolkit for conversions
invalid_input = True
def start() :
print ("Welcome to the converter toolkit made by Alan.")
op = input ("Please input what operation you wish to perform. 1 for Fahrenheit to Celsius, 2 for meters to centimetres and 3 for megabytes to gigabytes")
if op == "1":
#stuff
invalid_input = False # Set to False because input was valid
elif op == "2":
#stuff
invalid_input = False # Set to False because input was valid
elif op == "3": # you still have this as "if"; I would recommend keeping it as elif
#stuff
invalid_input = False # Set to False because input was valid
else:
print ("Sorry, that was an invalid command!")
while invalid_input: # this will loop until invalid_input is set to be False
start()
You can easily do it with loops, there are two types of loops
For Loops:
for i in range(0,5):
print 'Hello World'
While Loops:
count = 1
while count <= 5:
print 'Hello World'
count += 1
Each of these loops print "Hello World" five times
Python has control flow statements instead of goto statements. One implementation of control flow is Python's while loop. You can give it a boolean condition (boolean values are either True or False in Python), and the loop will execute repeatedly until that condition becomes false. If you want to loop forever, all you have to do is start an infinite loop.
Be careful if you decide to run the following example code. Press Control+C in your shell while it is running if you ever want to kill the process. Note that the process must be in the foreground for this to work.
while True:
# do stuff here
pass
The line # do stuff here is just a comment. It doesn't execute anything. pass is just a placeholder in python that basically says "Hi, I'm a line of code, but skip me because I don't do anything."
Now let's say you want to repeatedly ask the user for input forever and ever, and only exit the program if the user inputs the character 'q' for quit.
You could do something like this:
while True:
cmd = raw_input('Do you want to quit? Enter \'q\'!')
if cmd == 'q':
break
cmd will just store whatever the user inputs (the user will be prompted to type something and hit enter). If cmd stores just the letter 'q', the code will forcefully break out of its enclosing loop. The break statement lets you escape any kind of loop. Even an infinite one! It is extremely useful to learn if you ever want to program user applications which often run on infinite loops. If the user does not type exactly the letter 'q', the user will just be prompted repeatedly and infinitely until the process is forcefully killed or the user decides that he's had enough of this annoying program and just wants to quit.
write a for or while loop and put all of your code inside of it? Goto type programming is a thing of the past.
https://wiki.python.org/moin/ForLoop
You need to use a while loop. If you make a while loop, and there's no instruction after the loop, it'll become an infinite loop,and won't stop until you manually stop it.
def start():
Offset = 5
def getMode():
while True:
print('Do you wish to encrypt or decrypt a message?')
mode = input().lower()
if mode in 'encrypt e decrypt d'.split():
return mode
else:
print('Please be sensible try just the lower case')
def getMessage():
print('Enter your message wanted to :')
return input()
def getKey():
key = 0
while True:
print('Enter the key number (1-%s)' % (Offset))
key = int(input())
if (key >= 1 and key <= Offset):
return key
def getTranslatedMessage(mode, message, key):
if mode[0] == 'd':
key = -key
translated = ''
for symbol in message:
if symbol.isalpha():
num = ord(symbol)
num += key
if symbol.isupper():
if num > ord('Z'):
num -= 26
elif num < ord('A'):
num += 26
elif symbol.islower():
if num > ord('z'):
num -= 26
elif num < ord('a'):
num += 26
translated += chr(num)
else:
translated += symbol
return translated
mode = getMode()
message = getMessage()
key = getKey()
print('Your translated text is:')
print(getTranslatedMessage(mode, message, key))
if op.lower() in {'q', 'quit', 'e', 'exit'}:
print("Goodbye!")
return