Tip Calculator

And now for my Wizard tip calculator.

— Morty Seinfeld

In the United States, it’s customary to leave a tip for your server after dining in a restaurant, typically an amount equal to 15% or more of your meal’s cost. Not to worry, though, we’ve written a tip calculator for you, below!

def main():
    dollars = dollars_to_float(input("How much was the meal? "))
    percent = percent_to_float(input("What percentage would you like to tip? "))
    tip = dollars * percent
    print(f"Leave ${tip:.2f}")


def dollars_to_float(d):
    # TODO


def percent_to_float(p):
    # TODO


main()

Well, we’ve written most of a tip calculator for you. Unfortunately, we didn’t have time to implement two functions:

  • dollars_to_float, which should accept a str as input (formatted as $##.##, wherein each # is a decimal digit), remove the leading $, and return the amount as a float. For instance, given $50.00 as input, it should return 50.0.
  • percent_to_float, which should accept a str as input (formatted as ##%, wherein each # is a decimal digit), remove the trailing %, and return the percentage as a float. For instance, given 15% as input, it should return 0.15.

Assume that the user will input values in the expected formats.

Hints

Demo

Before You Begin

Log into code.cs50.io, click on your terminal window, and execute cd by itself. You should find that your terminal window’s prompt resembles the below:

$

Next execute

mkdir tip

to make a folder called tip in your codespace.

Then execute

cd tip

to change directories into that folder. You should now see your terminal prompt as tip/ $. You can now execute

code tip.py

to make a file called tip.py. Copy and paste the code above into a file, and complete the implementations of dollars_to_float and percent_to_float, replacing each TODO with one or more lines of your own code.

How to Test

Here’s how to test your code manually:

  • Run your program with python tip.py. Type $50.00 and press Enter. Then, type 15% and press Enter. Your program should output:
    Leave $7.50    
    
  • Run your program with python tip.py. Type $100.00 and press Enter. Then, type 18% and press Enter. Your program should output:
    Leave $18.00
    
  • Run your program with python tip.py. Type $15.00 and press Enter. Then, type 25% and press Enter. Your program should output
    Leave $3.75
    

You can execute the below to check your code using check50, a program that CS50 will use to test your code when you submit. But be sure to test it yourself as well!

check50 cs50/problems/2022/python/tip

Green smilies mean your program has passed a test! Red frownies will indicate your program output something unexpected. Visit the URL that check50 outputs to see the input check50 handed to your program, what output it expected, and what output your program actually gave.

How to Submit

In your terminal, execute the below to submit your work.

submit50 cs50/problems/2022/python/tip