This question already has answers here:
Breaking out of nested loops [duplicate]
(8 answers)
Asking the user for input until they give a valid response
(22 answers)
Closed 2 years ago.
As I am a new learner in python, I was trying to do an exercise having while loop in it.
I have written a piece of code which will ask user to enter his details.
After getting all the details the program should stop, but In my case after entering Account Number, it again start asking Mobile number to enter.
Please have a look at the code and suggest where I am going wrong.
bnkName = ["SBI", "PNB", "CBI", "ICICI", "BOB"]
targetattmpt = 10
appliedattmpt = 1
while (appliedattmpt <= targetattmpt):
mobilenum = input("Please Enter your Mobile Number:\n")
if (len(mobilenum) == 10):
while (True):
Bankname = input("Please Enter your Bank Name\n").upper()
if Bankname in bnkName:
print("Valid Bank\n")
print("Please enter your Account Number\n")
accnum = input("Account Number:\n")
print(accnum)
break
else:
print("Invalid Bank")
else:
print(mobilenum, "IS NOT VALID!!!", "You have", targetattmpt - appliedattmpt, "attempts left\n")
appliedattm = appliedattm + 1
if (appliedattmpt > targetattmpt):
print("Account locked!!")
The break statement inside the inner loop will break the inner loop but not the outer. You should re-think the logic and maybe add bool variable to check if inner loop broke so you can break the outer loop. For/while loops have else statements which will check if the loop called finished successfully or was aborted with a break. In the case of a while loop, the else will be executed if the condition in the is no longer true.
Take a look at: https://book.pythontips.com/en/latest/for_-_else.html
To give you an example:
j = 0
bank = True
while(j < 2):
print('check_this')
i = 0
while(i < 2):
print('check that')
if bank:
break
else:
i += 1
else:
break
print('I checked both !')
j += 1
Output:
check_this
check that
I checked both !
check_this
check that
I checked both !
Now change the bank to False
j = 0
bank = False
while(j < 2):
print('check_this')
i = 0
while(i < 2):
print('check that')
if bank:
break
else:
i += 1
else:
break
print('I checked both !')
j += 1
Output:
check_this
check that
check that
Related
This question already has answers here:
How do I get a result (output) from a function? How can I use the result later?
(4 answers)
Closed 5 months ago.
I am trying to use two variables (i, and q) across three functions. I want to test whether i and q are valid after each input . If they are then they will be added to list and the while loop continues. If they are not valid Then the function will stop and all input will be taken and presented. I have tried to make both i and q global variables but it does not seem to work as it is saying that "i" is not defined. How do I check the i and q variables in separate functions?
Any help would be really appreciated as I am only new and thought this should work.
I didn't know what to add so I have put down the three functions in full below:
Updated:
def add_item():
code_inputed = []
quan_inputed = []
VC()
VQ()
vc_result = VC(I)
vq_result = VQ(q)
while True:
if i != "END":
if vc_result == True and vq_result == True:
code_inputed.append(int(i))
quan_inputed.append(int(q))
elif vc_result == True and vq_result == False:
print("Invalid Quanity")
break
elif vc_result == False and vq_result == True:
print ("Invalid code")
break
else:
print("Invalid inputs")
break
return code_inputed,quan_inputed
def VC():
i = input("enter code: ")
minimum = 0
maxiumum = 39
if i == "END":
return False
elif int(i) > minimum and int(i) <= maximum:
True
else:
False
def VQ():
q = input("enter quantity: ")
minimum = 0
maxiumum = 49
if int(q) > minimum and int(q):
True
else:
False
Thank you for any help
Please read this W3Schools - Python global variables for a better understanding of how global variables work.
I think the problem with your code is, you should initialize your variables i and q first, before the add_item() function, and then get them from the global scope using the global keyword in the add_item function too.
i = 0
def add_item():
global i
Plus, you want to recheck your add_item() conditions,
while True:
i = input("enter code: ")
return i
if i != "END":
q = input("enter quantity: ")
return q # your code stops at this return
VC()
VQ()
if VC == True and VQ == True:
code_inputed.append(int(i))
quan_inputed.append(int(q))
elif VC == True and VQ == False:
print("Invalid Quanity")
break
elif VC == False and VQ == True:
print ("Invalid code")
break
else:
print("Invalid inputs")
break
P.S. you actually don't have to use global variables in this context, you can just pass the values as functions arguments.
Looks like you need some help here. First of all the global keyword is for functions where you are setting the global variable. Also, forget about globals. Pass i and q to the functions directly. Then set those calls equal to variables and check those variables.
vc_result = VC(i)
vq_result = VQ(q)
if vc_result == True and vq_result == True:
...
Plus, return immediately exits the function so no processing will continue. Those should be removed. I recommend reviewing tutorials on python functions to fill in your knowledge.
I need your help regarding the loop in a Python program. Can anyone show me how to loop the program below, like when I enter a wrong value it will keep prompting me to re-enter the value until it gets the correct values and moves to the next state.
I am trying the "while" loop but unsuccessful.
# Determine cleaning type
def CleaningType ():
while True:
# Prompt user to input Light or Complete cleaning type
cleanType = int(input("\n\tPlease select your cleaning type:\n(1) Light\n(2) Complete\n"))
if (cleanType == 1):
cleanCost = 20
elif (cleanType == 2):
cleanCost = 40
else:
# Display error msg
print("\t*** Invalid - Please re-enter your value...")
False
return (cleanType, cleanCost)
# Get number of rooms --------------------------------
def GetNumRooms ():
while True
# Prompt and get user reponse for number of rooms
numRooms = int(input('How many rooms would you like to be serviced (1-10)?\n'))
if (numRooms > 0 and numRooms <= 3):
print("\n\tYour cleaning size is small which costs $15 per room")
roomCost = 10
elif (numRooms > 3 and numRooms <= 5):
print("\n\tYour cleaning size is small which costs $25 per room")
roomCost = 15
elif (numRooms > 5 and numRooms <= 10):
print("\n\tYour cleaning size is small which costs $35 per room")
roomCost = 20
False
return (numRooms, roomCost)
You could use break to end the while loop when one of the current answers are submitted.
You can use a break statement to end a loop. Also, a function can call itself, like this:
# Determine cleaning type
def CleaningType ():
while True:
# Prompt user to input Light or Complete cleaning type
cleanType = int(input("\n\tPlease select your cleaning type:\n(1) Light\n(2) Complete\n"))
if (cleanType == 1):
cleanCost = 20
break
elif (cleanType == 2):
cleanCost = 40
break
else:
# Display error msg
print("\t*** Invalid - Please re-enter your value...")
CleaningType()
CleaningType()
I am running into a little problem that I cannot figure out. I am getting stuck in a while loop. I have 3 while loops, the first one executes as planned and then goes into the second. But then it just gets stuck in the second and I cannot figure out why.
A little explanation on what I am trying to do:
I am suppose to get 3 inputs: years of experience (yearsexp), performance (performance) and a random int generated between 1-10(level). The program will ask the user for their experience, if it is between 3-11 they are qualified. If not, it will tell them they are not qualified and ask to re-enter a value. Same thing with performance. If they enter a number less than or equal to 11 it will procede to generate the random int (level) at which point level will be used to asses their bonus. The user gets prompted for experience and will function correctly and proceed to performace. However, even when entering a valid input, it keeps asking them to re-enter the performance #. I cannot figure out why its getting stuck this way.
import random
error = True
expError = True
performanceError = True
# Get users name
name = input("Enter your name: ")
# Get users experience *MINIMUM of 3 yrs py
while (expError):
try:
yearsexp = int (input(name+", Enter the years of your experience: "))
if (yearsexp >= 3 and yearsexp <= 11):
expError = False
print(name, "You are qualified")
else:
raise ValueError
except:
print ("You have entered an invalid number! Try again...")
#Get users performance
while (performanceError):
try:
performance = int (input(name+", Enter the performance: "))
if (performance <= 11):
expError = False
print(name, "You are qualified")
else:
raise ValueError
except:
print ("You have entered an invalid number! Try again...")
performanceError = False
# Get random level number
level = random.randint(1,11)
print ("Random Level: ", end =' ')
print (level)
bonus = 5000.00
while (error):
try:
if (level >=5 and level <=8):
error = False
print ("Expected Bonus: $5,000.00")
print (name + ", your bonus is $", end =' ')
print (bonus)
elif (level <= 4 ):
error = False
bonus = bonus * yearsexp * performance * level
print ("Expected bonus: ", end =' ')
print (bonus)
print (name + ", your bonus is $", end =' ')
print (bonus)
else:
raise ValueError
except:
print ("You do not get a bonus")
You didn't set the performanceError to False
if (performance <= 11):
expError = False
needs to be changed to
if (performance <= 11):
performanceError= False
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