Develop Reference

Confused about if statements and functions

I'm very familiar with the random module but I always stumbled when it came to functions. How do I make a function only occur if it meets a certain condition? It gives me no output when im trying to validate my answer...
choice = input ("Which type of password would you like to generate? \n 1. Alphabetical \n")
if choice == 1:
characters = list(string.ascii_letters)
def generate_random_abc_password():
length = int(input("Enter password length: "))
random.shuffle(characters)
password = []
for i in range(length):
password.append(random.choice(characters))
random.shuffle(password)
print("".join(password))
generate_random_abc_password()

Seems like the most common mistake among beginners. When you use an input() function, it will return you some number/text/float or decimal number but in string type. For example
x = input("Enter your number")
# If i would input 2, my x variable would contain "2"
# 3 => "3"
# 550 => "550" and so on...
To avoid such a problem and to store your value in proper type, you need to wrap your input with int() function, as shown below
x = int(input(("Enter your number"))
# From now, whenever i prompt any number from my keyboard, it will
# be an integer number, which i can substract, add, multiply and divide.
As simple as it is. Happy learning!

You should convert the input to integer as by default the data type for input is string.
Alternatively rather than changing input data type you can compare it with the str(1) or change if choice == 1: to if choice == '1':
You can try using :
import string
import random
choice = int(input ("Which type of password would you like to generate? \n 1. Alphabetical \n"))
if choice == 1:
characters = list(string.ascii_letters)
def generate_random_abc_password():
length = int(input("Enter password length: "))
random.shuffle(characters)
password = []
for i in range(length):
password.append(random.choice(characters))
random.shuffle(password)
print("".join(password))
generate_random_abc_password()
The above code will result in :
Which type of password would you like to generate?
1. Alphabetical
1
Enter password length: 10
MEQyTcspdy

The problem here is that you've defined the characters variable in your if block. That is your function is not aware of of the variable that is why you should pass the characters variable as a input to the function the code should look like
choice = input ("Which type of password would you like to generate? \n 1. Alphabetical \n")
if choice == 1:
characters = list(string.ascii_letters)
def generate_random_abc_password(characters):
length = int(input("Enter password length: "))
random.shuffle(characters)
password = []
for i in range(length):
password.append(random.choice(characters))
random.shuffle(password)
print("".join(password))
generate_random_abc_password(characters)
A function works like an isolated piece of code it takes it's own inputs and returns it's own outputs or does it's stuff.
As well as the input isn't casted to an int as the above mentioned answer says...

(Python) Try and Except within a User-Defined Function

I have worked on many projects (school projects, I'm not too advanced), and have found that in many programs where I require the user to input a value that is an integer, or decimal(float), I need to use a "try-except" statement, within a while loop, in order to make certain that the user inputs the required value type.
For example:
def main():
userValue = input("Please enter an integer: ")
while(True):
try:
userValue = int(userValue)
break
except:
userValue = input("That is not an integer, try again: ")
print("The integer you entered is: " + str(userValue))
main()
# Input: SADASD (A non-integer value)
# Output: "That is not an integer, try again: "
# Second-Input: 3
# Second-Output: "The integer you entered is: 3"
Understandably, typing out this entire section of code repeatedly, in a program that requires user input multiple times, is not really efficient. So understanding, that user-defined functions help when I need to perform one action, multiple times. With this in mind, I defined my own function with that same try-except statement in a while loop. However, now, when I use the function, instead of printing the same output previously, rather, it prints out the first value the user had input.
For example:
def valueCheck_Integer(userInput):
while(True):
try:
userInput= int(userInput)
break
except:
userInput = input("That is not an integer, try again: ")
def main():
userValue = input("Please enter an integer: ")
valueCheck_Integer(userValue)
print("The integer you entered is: " + str(userValue))
main()
# Input: SADASD (A non-integer value)
# Output: "That is not an integer, try again: "
# Second-Input: SASASD
# Second-Output: "That is not an integer, try again: "
# Third-Input: 3
# Third-Output: SADASD (The first value that the user Input, instead of 3)
Can someone please explain to me why this happens, and some suggestions on how to fix it?
Thank you!

It's probably going to be easier to expect the function to get/check/return the integer rather than check input you already have. You can pass it the string to use for asking for the value (you could also pass the error string). It will keep asking until it's successful and then return the number you want:
def get_integer(question):
while(True):
try:
return int(input(question))
except ValueError:
question = "That is not an integer, try again:"
def main():
userValue = get_integer("Please enter an integer: ")
print("The integer you entered is: " + str(userValue))
main()

It is because of you are printing userValue instead of userInput.
I used return make it easier. So the code will be like this
def valueCheck_Integer(userInput):
while(True):
try:
userInput= int(userInput)
break
except:
userInput = input("That is not an integer, try again: ")
return userInput
def main():
userValue = input("Please enter an integer: ")
print("The integer you entered is: " + str(valueCheck_Integer(userValue)))
main()
You can make your code smaller like this:
def valueCheck_Integer(userInput):
while not(userInput.isdigit()):
userInput = input("That is not an integer, try again: ")
return userInput
def main():
userValue = input("Please enter an integer: ")
print("The integer you entered is: " + str(valueCheck_Integer(userValue)))
main()

First off, Good Question.
To understand what is going on, we first have to talk about scope of a variable.
When you define a variable outside a function, it becomes something called a global variable. This basically means that you can access it from anywhere in your code. When you define the variable within a function, it becomes a local variable. This means that it is only accessible from within your function. Finally, when a function gets passed in a variable, it gets its own local copy of the variable to work with.
Now let's look at your code.
when you call valueCheck_Integer(userInput): the function gets its own copy of userInput to work with. thus all the changes that the function does modifies the local userInput while the global userInput stays the same. As such, when the user enters a correct answer, the global userInput is the one that gets printed and the changes the function makes to local userInput is lost.
So, how can we fix this?
There are two main methods:
1)Using the global keyword
def valueCheck_Integer(userInput):
global userInput
while(True):
try:
userInput= int(userInput)
break
except:
userInput = input("That is not an integer, try again: ")
This keyword asks the function to modify the global userInput
2)Returning a value
def valueCheck_Integer(userInput):
while(True):
try:
userInput= int(userInput)
break
except:
userInput = input("That is not an integer, try again: ")
return userInput
def main():
userValue = input("Please enter an integer: ")
print("The integer you entered is: " + str(valueCheck_Integer(userValue)))
main()
This works by returning the local copy of userInput and modifying global userInput to equal local userInput
The second code I used was from
Osadhi Virochana Jayasinghe Si's answer.

It's because, if you see your line of code where you print the final output -:
print("The integer you entered is: " + str(userValue))
you will realise that the value you are printing is the one you take the first time from the input function. But this is not the value you have been working on to achieve in your other function.
So for you to rather get that value, the function in some way has to return it back to you.
For this you should allow the function to return the value in the last line.
like so -:
return userInput
and then change the line where you call function so it saves the value returned.
like so -:
userValue = valueCheck_Integer(userValue)
Also as mentioned by others using the global keyword you can define the variable in global scope.
But this is really not a good practice until really needed as it can increase the amount of space that the var is taking, before the variable only took the space for a limited time for when the function is called, but now the variable takes space throughout the time the program runs.
While return will not do so as it will only return the value and once assigned to the already defined variable it will remove the returned value from space.
This should hopefully fix your problem.
I hope this helps.
And also hope that you're safe during the time of this ongoing pandemic.

Incorrect if-else statements

I've been trying to write a function that will ask for a number between 1-11 and will randomly choose a number and will compare between them.
I can't figure out why no matter what number I type in (equals or smaller or bigger) it will always type the "Your number is less" message.
def loto():
_number = int(input("Enter any number between 1-10: "))
import random
for x in range(1):
print ("Python chose: " + str(random.randint(1,11)))
if ("_number" == "random"):
print ("You Won! :)")
if ("_number" < "random"):
print ("Your number is less")
if ("_number" > "random"):
print ("Your number is more")
else:
print ("You Lost :(")
loto()
I'm using Python 3.
Thanks:)

Your first problem is that you're comparing the strings "_number" and "random". ASCIIbetically (or, rather, Unicoderifically), "_number" < "random", because the _ character is #95 and the r character is #114.
If you want to compare two variables, you just refer to the variables, not strings that happen to be the same as the names of those variables.
Your second problem is that random isn't your random number, it's the module you used to create that number. And, more seriously, you aren't storing that number anywhere—you're just converting it to a string to print it out and then throwing it away.
Your third problem is that you need to change those ifs to elifs. Otherwise, the You Lost message gets printed whenever _number > random is not true, instead of only whenever all of the three comparisons are not true.
Putting that all together:
choice = random.randint(1,11)
for x in range(1):
print ("Python chose: " + str(choice))
if (_number == choice):
print ("You Won! :)")
elif (_number < choice):
print ("Your number is less")
elif (_number > choice):
print ("Your number is more")
else:
print ("You Lost :(")
Of course there's no way to actually lose your game—one of the three conditions is always going to be true. (If you were using complex numbers, or floats including NaN, you could input a number that wasn't comparable in any way to the selected one, but you're not.)
While we're at it:
There's no reason to name your variable _number instead of number.
That for x in range(1): loop doesn't do anything useful—it loops exactly once, setting x to 0, which you never use.
You don't need parentheses around your conditions.
You shouldn't import modules in the middle of a function like that except in special cases where you need unusual things like lazy loading.
You should follow PEP 8 style, or at least pick a consistent style to follow.
It's simpler to just pass multiple arguments to print, or to use string formatting, than to manually convert things to strings and concatenate them.
So:
import random
def loto():
number = int(input("Enter any number between 1-10: "))
choice = random.randint(1, 11)
print("Python chose:", choice)
if number == choice:
print("You Won! :)")
elif number < choice:
print("Your number is less")
elif number > choice:
print("Your number is more")
else:
print("You Lost :(")
loto()

You were comparing strings not variables, you need to remove quotes, and you not saved random number into a variable. The for loop is making one repetition only, you can remove it.
Update your cod like this:
import random
def loto():
_number = int(input("Enter any number between 1-10: "))
rand_number = random.randint(1,11) # can't had the same name as random
if (_number == rand_number):
print ("You Won! :)")
elif (_number < rand_number):
print ("Your number is less")
elif (_number > rand_number):
print ("Your number is more")
else:
print ("You Lost :(")
loto()

python calculator program [closed]

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Closed 10 years ago.
I wrote a simple calculator program by using functions, I don't know what exactly wrong with this code, its showing error. I did possible steps to debug this, but I couldn't.
#!/usr/bin/python
def add():
print "Enter the two numbers to Add"
A=int(raw_input("Enter A:"))
B=int(raw_input("ENter B:"))
c = A + B
def sub():
print "Enter the two numbers to Subtract"
A=int(raw_input("Enter A:"))
B=int(raw_input("Enter B:"))
c = A - B
def Mul():
print "Enter the two numbers to Multiply"
A=int(raw_input("Enter A:"))
B=int(raw_input("Enter B:"))
c = A * B
def Div():
print "Enter the two number to Divide"
A=float(raw_input("Enter A:"))
B=float(raw_input("Enter B:"))
c = A / B
print "1: ADDITION"
print "2: SUBTRACTION"
print "3: MULTIPLICATION"
print "4: DIVITION"
print "0: QUIT"
while true:
CHOICE = int(raw_input(("ENTER THE CORRESPONDING NUMBER FOR CALCULATION"))
if CHOICE == "1":
print 'ADDING TWO NUMBERS:'
add(c):
elif CHOICE == "2":
print 'SUBTRACTING TWO NUMBERS:'
sub(c):
elif CHOICE == "3":
print 'MULTIPLYING TWO NUMBERS:'
Mul(c):
elif CHOICE == "4":
print "DIVIDEING TWO NUMBERS"
Div(c):
elif CHOICE == "0":
return 0:
else
Print "The value Enter value from 1-4"
Error:
File "cal_fun.py", line 44
if CHOICE == "1":
^
SyntaxError: invalid syntax

I've have tried to cover all of the problems with your code, of which there are numerous.
Starting with syntax errors:
# true needed a captial T
while True:
# Brackets were mismatched
CHOICE = int(raw_input("ENTER THE CORRESPONDING NUMBER FOR CALCULATION"))
if CHOICE == "1":
print 'ADDING TWO NUMBERS:'
# Calling a function shouldn't have trailing :
add(c)
elif CHOICE == "2":
print 'SUBTRACTING TWO NUMBERS'
# Calling a function shouldn't have trailing :
sub(c)
elif CHOICE == "3":
print 'MULTIPLYING TWO NUMBERS'
# Calling a function shouldn't have trailing :
Mul(c)
elif CHOICE == "4":
print "DIVIDEING TWO NUMBERS"
# Calling a function shouldn't have trailing :
Div(c)
elif CHOICE == "0":
# can only return from a function use exit here instead
exit()
# else needs a trailing :
else:
# No capital P for print
print "The value Enter value from 1-4"
The code now has no syntax errors but still has many problems.
You pass c to your function, c is never initialized, what is c?
Your function doesn't take arguments def add(): (even though pass the mysterious c value).
Your function doesn't print or return the result it just computes.
You store CHOICE as an int are do comparisons with strings so the else case is always executed and there is no way to exit the loop (infinite looping).
Fixed code:
#!/usr/bin/python
def add():
print "Enter the two numbers to Add"
A=int(raw_input("Enter A: "))
B=int(raw_input("Enter B: "))
return A + B
def sub():
print "Enter the two numbers to Subtract"
A=int(raw_input("Enter A: "))
B=int(raw_input("Enter B: "))
return A - B
def mul():
print "Enter the two numbers to Multiply"
A=int(raw_input("Enter A: "))
B=int(raw_input("Enter B: "))
return A * B
def div():
print "Enter the two number to Divide"
A=float(raw_input("Enter A: "))
B=float(raw_input("Enter B: "))
return A / B
print "1: ADDITION"
print "2: SUBTRACTION"
print "3: MULTIPLICATION"
print "4: DIVITION"
print "0: QUIT"
while True:
CHOICE = int(raw_input("ENTER THE CORRESPONDING NUMBER FOR CALCULATION "))
if CHOICE == 1:
print 'ADDING TWO NUMBERS:'
print add()
elif CHOICE == 2:
print 'SUBTRACTING TWO NUMBERS'
print sub()
elif CHOICE == 3:
print 'MULTIPLYING TWO NUMBERS'
print mul()
elif CHOICE == 4:
print "DIVIDEING TWO NUMBERS"
print div()
elif CHOICE == 0:
exit()
else:
print "The value Enter value from 1-4"
The code is now functional.
Output:
1: ADDITION
2: SUBTRACTION
3: MULTIPLICATION
4: DIVITION
0: QUIT
ENTER THE CORRESPONDING NUMBER FOR CALCULATION 1
ADDING TWO NUMBERS:
Enter the two numbers to Add
Enter A: 2
Enter B: 5
7
ENTER THE CORRESPONDING NUMBER FOR CALCULATION 2
SUBTRACTING TWO NUMBERS
Enter the two numbers to Subtract
Enter A: 2
Enter B: 5
-3
ENTER THE CORRESPONDING NUMBER FOR CALCULATION 3
MULTIPLYING TWO NUMBERS
Enter the two numbers to Multiply
Enter A: 2
Enter B: 5
10
ENTER THE CORRESPONDING NUMBER FOR CALCULATION 4
DIVIDEING TWO NUMBERS
Enter the two number to Divide
Enter A: 2
Enter B: 5
0.4
ENTER THE CORRESPONDING NUMBER FOR CALCULATION 0
Functional but not perfect, for instance no error handling for erroneous input.

You're missing an end parenthesis on the previous line (a common cause of mysterious syntax errors), change:
CHOICE = int(raw_input(("ENTER THE CORRESPONDING NUMBER FOR CALCULATION"))
to
CHOICE = int(raw_input("ENTER THE CORRESPONDING NUMBER FOR CALCULATION"))
This is not the only syntax error in the program- you end many lines with : when you shouldn't, like:
add(c):
sub(c):
Mul(c):
Div(c):
You also
have no : for an else statement (it's required)
capitalize Print when it should be print
have a return statement outside of any function
There are also errors that are not syntax errors:
misspell True as true
compare CHOICE, an int, to a string like "1" or "2"
are passing a non-existent variable c to a function that takes no arguments

You are passing a variable c to your functions add() sub() etc. but they are defined to take no arguments.

on top of the syntax errors already mentioned what I think you actually want is for each function to return values to the main programme loop, which will then display them:
def add():
A=int(raw_input("Enter A:"))
B=int(raw_input("ENter B:"))
return A + B
...
while true:
CHOICE = int(raw_input(("ENTER THE CORRESPONDING NUMBER FOR CALCULATION"))
if CHOICE == "1":
print 'ADDING TWO NUMBERS:'
answer = add()
print answer
...
or alternatively make the programme shorter by inputting A and B in the main loop then passing those as parameters to the calculating functions:
def add():
return A + B
...
while true:
CHOICE = int(raw_input(("ENTER THE CORRESPONDING NUMBER FOR CALCULATION"))
A=int(raw_input("Enter A:"))
B=int(raw_input("ENter B:"))
if CHOICE == "1":
print 'ADDING TWO NUMBERS:'
answer = add(A, B)
print answer
...

Using random.randint help in python

The following code is my attempt at simulating a lottery.
import random
def lottery(numbers):
lottoNumbers = [randint('0,100') for count in range(3)]
if numbers == lottoNumbers:
print('YOU WIN $10,000')
else:
print('YOU LOSE,DUN DUN DUNNN!')
return numbers
def main():
numbers = int(input('Enter a number: '))
if numbers == lottoNumbers:
numbers = lottery(numbers)
else:
numbers = lottery(numbers)
main()
Hey guys I've gotten this far with the help you've given me. I'm trying to write the code so that 3 lotto numbers at random will be chosen. Then the user must enter 3 of his/her own lotto numbers. If they get all 3 correct then they win the whole prize, if they get the 3 numbers but not in the correct order they win some of the prize. Obviously if they guess all wrong then a print statement would state that. What I'm confused about is how can I write the code so that the user can enter 3 numbers to try matching the random lottery numbers. I also want to print the 3 lottery numbers after the user inputs his/her choices. Any ideas guys?
Thanks for your help everyone.

You seem a bit confused about what the role of the arguments in a function are. You've said that your randm function takes the argument "number", but then you haven't actually used it anywhere. The next time number appears, you've assigned it a completely new value, so any value passed to randm isn't actually being used.
Also, the function is trying to return x, when x hasn't been assigned within the function. Either you already have a global variable called x already defined, in which case the function will just return that variable, or the function will just fail because it can't find the variable x.
Here's a quick example I've done where you pass their three numbers as a list as an argument to the function.
import random
theirNumbers=[5,24,67]
def checkNumbers(theirNumbers):
lottoNumbers = []
for count in range(3)
lottoNumbers.append(random.randint(0,100))
winning = True
for number in theirNumbers:
if not each in lottoNumbers: winning=False
if winning == True: print("Winner!")

There are a few things wrong with your implementation, to name a few:
if you are trying to compare the output of the function randm to x, you will need to include a return value in the function, like so:
def randm():
return return_value
You appear to be printing all the values but not storing them, in the end you will only end up with the final one, you should attempt to store them in a list like so:
list_name = [randint(0,100) for x in range(x)]
This will generate randint(0,100) x times in a list, which will allow you to access all the values later.
To fix up your code as close to what you were attempting as possible I would do:
import random
def randm(user_numbers):
number = []
for count in range(3):
number.append(random.randint(0, 100))
print(number)
return user_numbers == number
if randm(x):
print('WINNER')
If you are looking for a very pythonic way of doing this task,
you might want to try something like this:
from random import randint
def doLotto(numbers):
# make the lotto number list
lottoNumbers = [randint(0,100) for x in range(len(numbers))]
# check to see if the numbers were equal to the lotto numbers
if numbers == lottoNumbers:
print("You are WinRar!")
else:
print("You Lose!")
I'm assuming from your code (the print() specifically) that you are using python 3.x+

Try to post your whole code. Also mind the indentation when posting, there it looks like the definition of your function would be empty.
I'd do it like this:
import random
def lottery():
win = True
for i in range(3):
guess = random.randint(1,100)
if int(raw_input("Please enter a number...")) != guess:
win = False
break
return win

Let so do this in few steps.
First thing you should learn in writing code is to let separate pieces of code( functions or objects) do different jobs.
First lets create function to make lottery:
def makeLottery(slotCount, maxNumber):
return tuple(random.randint(1,maxNumber) for slot in range(slotCount))
Next lets create function to ask user's guess:
def askGuess(slotCount, maxNumber):
print("take a guess, write {count} numbers separated by space from 1 to {max}".format(count = self.slotCount, max = self.maxNumber))
while True: #we will ask user until he enter sumething suitable
userInput = raw_input()
try:
numbers = parseGuess(userInput,slotCount,maxNumber)
except ValueError as err:
print("please ensure your are entering integer decimal numbers separated by space")
except GuessError as err:
if err.wrongCount: print("please enter exactly {count} numbers".format(count = slotCount))
if err.notInRange: print("all number must be in range from 1 to {max}".format(max = maxNumber))
return numbers
here we are using another function and custom exception class, lets create them:
def parseGuess(userInput, slotCount,maxNumber):
numbers = tuple(map(int,userInput.split()))
if len(numbers) != slotCount : raise GuessError(wrongCount = True)
for number in numbers:
if not 1 <= number <= maxNumber : raise GuessError(notInRange = True)
return numbers
class GuessError(Exception):
def __init__(self,wrongCount = False, notInRange = False):
super(GuessError,self).__init__()
self.wrongCount = wrongCount
self.notInRange = notInRange
and finally function to check solution and conratulate user if he will win:
def checkGuess(lottery,userGuess):
if lottery == userGuess : print "BINGO!!!!"
else : print "Sorry, you lost"
As you can see many functions here uses common data to work. So it should suggest you to collect whole code in single class, let's do it:
class Lottery(object):
def __init__(self, slotCount, maxNumber):
self.slotCount = slotCount
self.maxNumber = maxNumber
self.lottery = tuple(random.randint(1,maxNumber) for slot in range(slotCount))
def askGuess(self):
print("take a guess, write {count} numbers separated by space from 1 to {max}".format(count = self.slotCount, max = self.maxNumber))
while True: #we will ask user until he enter sumething suitable
userInput = raw_input()
try:
numbers = self.parseGuess(userInput)
except ValueError as err:
print("please ensure your are entering integer decimal numbers separated by space")
continue
except GuessError as err:
if err.wrongCount: print("please enter exactly {count} numbers".format(count = self.slotCount))
if err.notInRange: print("all number must be in range from 1 to {max}".format(max = self.maxNumber))
continue
return numbers
def parseGuess(self,userInput):
numbers = tuple(map(int,userInput.split()))
if len(numbers) != self.slotCount : raise GuessError(wrongCount = True)
for number in numbers:
if not 1 <= number <= self.maxNumber : raise GuessError(notInRange = True)
return numbers
def askAndCheck(self):
userGuess = self.askGuess()
if self.lottery == userGuess : print "BINGO!!!!"
else : print "Sorry, you lost"
finally lets check how it works:
>>> lottery = Lottery(3,100)
>>> lottery.askAndCheck()
take a guess, write 3 numbers separated by space from 1 to 100
3
please enter exactly 3 numbers
1 10 1000
all number must be in range from 1 to 100
1 .123 asd
please ensure your are entering integer decimal numbers separated by space
1 2 3
Sorry, you lost
>>> lottery = Lottery(5,1)
>>> lottery.askAndCheck()
take a guess, write 5 numbers separated by space from 1 to 1
1 1 1 1 1
BINGO!!!!