向变量加一个小数点后两位的数字（2.50）

Question

How do I add 2.50 to the cost?

Right now it just prints it out as 2.

cost = 0.00

r = open("toppings.txt")

bases = ["small","medium","large"]

toppings = ["Pepperoni","Chicken","Cajun Chicken","Mushrooms",
            "Red Onions","Sweetcorn","Ham","Cheese","Spicy Minced Beef",
            "Anchovies","Tuna","Peppers","Jalapenos","Green Chillies"] #0-13

def small():

    current = cost + 2.50

    print("Your current total cost is " + "£" + str(int(current)))

Answer 1

There are two problems:

• You loose the decimal places as soon as you convert it to an int in int(current) .
• If you always want two decimal places you have to use some sort of string formatting.

I would advise just to use str.format with "2" decimal places (here enforced by the .2f ):

'Your current total cost is £ {:.2f} '.format(current)

If you're working with "money"-like variables you should use decimal.Decimal instead of floats, just so you don't need to take care of the "inexactness" of floating point numbers.

Answer 2

You are converting your float current bill amount to int in this line

print("Your current total cost is " + "£" + str(int(current)))

Instead use this command to print your current bill amount.

print("Your current total cost is " + "£" + "{0:.2f}".format(round(current,2)))

output

Your current total cost is £5.50

Answer 3

int turns a number into a whole number. For example, int(2.1) = 2

Your last line should have just str(current) .

print("Your current total cost is " + "£" + str(current))