Vending Machine Program: Problem with variables

[icabero0225]

I'm trying to make a simple vending machine program. Running this program gives me this error:

Error:
Traceback (most recent call last):
  File "C:/Users/ignacio cabero/Desktop/Python/vendingmachine.py", line 13, in <module>
   insertp25()
 File "C:/Users/ignacio cabero/Desktop/Python/vendingmachine.py", line 11, in insertp25
   total_insert += 0.25
UnboundLocalError: local variable 'total_insert' referenced before assignment

global total_cost, total_insert
total_cost=0
total_insert=0

float(total_cost)
float(total_insert)
def insertp25():
   total_insert += total_insert + 0.25
   print(total_insert)
insertp25()
insertp25()

What can I do? I made the variables global yet nothing seems to work.

[wavic]

global statement is for use in a function to reference to a global variable not local

[buran]

to elaborate further on what wavic said, here is how it should be

total_insert=0.0

def insertp25():
    global total_insert
    total_insert +=  0.25
    print(total_insert)
insertp25()
insertp25()

note that your line 8 is incorrect. it should be either like in my code above (line 5) or like this

total_insert = total_insert + 0.25

note that using globals is considered bad programming practice. you should pass arguments to functions instead.

total_insert=0.0

def insertp25(total):
    total +=  0.25
    print(total)
    return total

total_insert = insertp25(total_insert)
total_insert = insertp25(total_insert)

That said, it's obvious that using function is somewhat redundant. It only complicates the code. In a more advanced approach you would use class, e.g.

class VendingMachine(object):
    accepted_coins = (0.25, 0.50, 1.00, 2.00)
    drinks = {'coffee':0.50, 'tee':1.00}

    def __init__(self):
        self.total = 0.00

    def insert_coin(self, coin):
        if float(coin) not in self.accepted_coins:
            print('The machine accepts only: {}.'.format(self.accepted_coins), end=' ')
        else:
            self.total += coin
        print('Total of {:.2f} in the machine'.format(self.total))

    def buy(self, buy_drink):
        buy_drink = buy_drink.lower()
        if buy_drink not in self.drinks:
            print("We don't have {}. You can buy only:".format(buy_drink))
            for drink, price in sorted(self.drinks.items()):
                print('{} for {:.2f}'.format(drink, price))
        elif self.total < self.drinks[buy_drink]:
            print('Not enough money in the machine. Please insert {:.2f} more'.format(self.drinks[buy_drink] - self.total))
        else:
            self.total -= self.drinks[buy_drink]
            print('Take your {}. Total of {:.2f} in the machine'.format(buy_drink, self.total))



vm = VendingMachine()
vm.insert_coin(0.25)
vm.insert_coin(0.25)
vm.insert_coin(0.75)
vm.insert_coin(1.0)
vm.buy('tee')
vm.buy('tee')
vm.insert_coin(0.50)
vm.buy('tee')
vm.buy('juice')

Output:
Total of 0.25 in the machine
Total of 0.50 in the machine
The machine accepts only: (0.25, 0.5, 1.0, 2.0). Total of 0.50 in the machine
Total of 1.50 in the machine
Take your tee. Total of 0.50 in the machine
Not enough money in the machine. Please insert 0.50 more
Total of 1.00 in the machine
Take your tee. Total of 0.00 in the machine
We don't have juice. You can buy only:
coffee for 0.50
tee for 1.00

Of course, this is only sample implementation.