Working with functions (basic Python)
I'm a beginner in programming ( python ) and doing some recent homework, but I'm really stuck with this simple function implementation. Basically, I have to ask for user input done in main (), then define another function to compute the computation with variables assigned for user input. When run in IDLE it will output 0. Any help or hints would be extremely helpful, thanks. Here is the code I have so far:
#global variables
firstClass = 0.0
businessClass = 0.0
economyClass = 0.0
soldFirstClass = 0.0
soldBusinessClass = 0.0
soldEconomyClass = 0.0
totalFC = 0.0
totalBC = 0.0
totalEC = 0.0
######################################
###########MAIN FUNCTION#############
######################################
def main():
print('***WELCOME***\n')
print('***Please ENTER the Airlines ticket prices***\n')
firstClass = float(input ('Please ENTER a ticket price for First Class: '))
businessClass = float(input ('Please ENTER a ticket price for Business Class: '))
economyClass = float(input ('Please ENTER a ticket price for Economy Class: '))
print('\nThank You\n')
soldFirstClass = float(input ('Please ENTER the number of sold tickets for First Class: '))
soldBusinessClass = float(input ('Please ENTER the number of sold tickets for Business Class: '))
soldEconomyClass = float(input ('Please ENTER the number of sold tickets for Economy Class: '))
calcClass()
def calcClass():
global firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass
totalFC = firstClass*soldFirstClass
print('Total money earned for First Class = %0.0f ') % totalFC
totalBC = businessClass*soldBusinessClass
print('Total money earned for Business Class = %0.0f ') % totalBC
totalEC = economyClass*soldEconomyClass
print('Total money earned for Economy Class = %0.0f ') % totalEC
main()
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Yours main()
is assigning local variables. Copy the operator global …
from calcClass()
to main()
.
Having said that, using globals to pass information around is almost always a bad idea. You must pass them as parameters:
# No globals; just go straight into main
def main():
print('***WELCOME***\n')
print('***Please ENTER the Airlines ticket prices***\n')
firstClass = float(input ('Please ENTER a ticket price for First Class: '))
⋮
calcClass(firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass)
def calcClass(firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass):
totalFC = firstClass*soldFirstClass
print('Total money earned for First Class = %0.0f ') % totalFC
⋮
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The first problem in your code is what you are using global
backwards (this is actually one of the most confusing things in python).
Use global to declare which variables from the global scope you want to write (you use it to define the variables you want to read). As long as you don't write a variable with the same name as a global variable, you can read it from that global without using the global declaration.
Accordingly, the smallest change you can make to your code to make it work is to add the correct global declarations to both of your functions, identifying the global variables that you will assign.
However, the right thing to do is eliminate any globals you want to write. Instead, add parameters to your functions and pass values between them using parameters.
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Don't use global variables. Instead, let's calcClass
take arguments, like this:
totalFC = 0.0
totalBC = 0.0
totalEC = 0.0
def main():
print('***WELCOME***\n')
print('***Please ENTER the Airlines ticket prices***\n')
firstClass = float(input ('Please ENTER a ticket price for First Class: '))
businessClass = float(input ('Please ENTER a ticket price for Business Class: '))
economyClass = float(input ('Please ENTER a ticket price for Economy Class: '))
print('\nThank You\n')
soldFirstClass = float(input ('Please ENTER the number of sold tickets for First Class: '))
soldBusinessClass = float(input ('Please ENTER the number of sold tickets for Business Class: '))
soldEconomyClass = float(input ('Please ENTER the number of sold tickets for Economy Class: '))
calcClass(firstClass, businessClass, economyClass, soldFirstClass, soldBusinessClass, soldEconomyClass)
def calcClass(firstClass, businessClass, economyClass, soldFirstClass, soldBusinessClass, soldEconomyClass):
totalFC = firstClass*soldFirstClass
print('Total money earned for First Class = %0.0f ') % totalFC
totalBC = businessClass*soldBusinessClass
print('Total money earned for Business Class = %0.0f ') % totalBC
totalEC = economyClass*soldEconomyClass
print('Total money earned for Economy Class = %0.0f ') % totalEC
if __name__ == '__main__':
main()
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I think you just made a small mistake.
In this module, "Main Function" is main()
also a function similar to "calcClass ()".
So, when you want to use these globals in main()
, you must add this operator to the main function as you did for the functioncalcClass()
global firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass
So the main function looks like this:
def main():
# NOTE THIS LINE.
global firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass
print('***WELCOME***\n')
print('***Please ENTER the Airlines ticket prices***\n')
firstClass = float(input ('Please ENTER a ticket price for First Class: '))
businessClass = float(input ('Please ENTER a ticket price for Business Class: '))
economyClass = float(input ('Please ENTER a ticket price for Economy Class: '))
print('\nThank You\n')
soldFirstClass = float(input ('Please ENTER the number of sold tickets for First Class: '))
soldBusinessClass = float(input ('Please ENTER the number of sold tickets for Business Class: '))
soldEconomyClass = float(input ('Please ENTER the number of sold tickets for Economy Class: '))
calcClass()
Or else, you could do it instead by declaring the function arguments calcClass()
and passing those variables as parameters.
this is how the code will look like:
def main():
print('***WELCOME***\n')
print('***Please ENTER the Airlines ticket prices***\n')
firstClass = float(input ('Please ENTER a ticket price for First Class: '))
businessClass = float(input ('Please ENTER a ticket price for Business Class: '))
economyClass = float(input ('Please ENTER a ticket price for Economy Class: '))
print('\nThank You\n')
soldFirstClass = float(input ('Please ENTER the number of sold tickets for First Class: '))
soldBusinessClass = float(input ('Please ENTER the number of sold tickets for Business Class: '))
soldEconomyClass = float(input ('Please ENTER the number of sold tickets for Economy Class: '))
# NOTE THIS LINE
calcClass(firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass)
# NOTE THIS LINE
def (calcClass firstClass, soldFirstClass, businessClass, soldBusinessClass, economyClass, soldEconomyClass):
totalFC = firstClass*soldFirstClass
print('Total money earned for First Class = %f ') % totalFC
totalBC = businessClass*soldBusinessClass
print('Total money earned for Business Class = %f ') % totalBC
totalEC = economyClass*soldEconomyClass
print('Total money earned for Economy Class = %f ') % totalEC
main()
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