Decimal Subtraction

Help, Im writing a vending machine based program, and the user's credit is re-displayed to the user when they purchase an item, but all prices are in decimal form. But when I purch

Solution 1:

So your code bugged me alot. I made some changes to make things more pythonic...

1. Instead of separate lists for your menu, I made it a list of tuples containing the product and it's price
2. I fixed your float casts

There's alot to be done for example, catching errors on invalid inputs, checking for available credit before subtracting price, etc...

products = [
    ("Kinder Bueno", 0.65),
    ("Doritos Chilli Heatwave", 0.70),
    ("Nestle Yorkie Bar", 0.50),
    ("Coca Cola(Can)", 0.70),
    ("Volvic Stawberry Water", 0.80)
]  
min_price = min(products, key=lambda x:x[1])[1]
credit = float(raw_input("Please input your change, CAREFUL! This Machine only accepts 10p,20p,50p and £1: \n Please enter your change in Pence, at least {0} (Decimal form). e.g' 1.35  ".format(min_price)))

while credit < min_price:
    credit += float(raw_input("Please input more change, you have {0} available, please input at least {1} more: ".format(credit, min_price - credit)))

print"You have {0} credit available.".format(credit)
print"The product selection is the following:"for i, (product, price) inenumerate(products):
    print"  {0}) {1} {2}".format(i, product, price)

selection = int(raw_input("Please select a product: "))

if0 >= selection < len(products):
    product, price = products[selection]
    print"You bought {0} for {1}".format(product, price)
    new_credit = credit - price
    print"Your remaining credit is: ", new_credit

With the list of tuples, you can easily get a minimum price to ensure the user has enough to actually buy something:

min_price = min(products, key=lambda x:x[1])[1]

which gets the tuple with the lowest price and stores just the price in min_price