Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python

Gary Gibson
Gary Gibson
5,011 Points

How to catch a value error on the bottom of this shopping list script?

Kenneth said to catch value errors at the bottom of this script. I've tried a few times but can't get it to work properly.

shopping_list = []

def show_help():
    print("\nSeparate each item with a comma.")
    print("""Type 'done' to quit, 'show' to see the curent list, 
and 'help' to get this message as a reminder.""")

def show_list():
    count = 1
    for i in shopping_list:
        print("{}: {}".format(count, i))
        count += 1

print("Enter items for your shopping list.")
show_help()

while True:
    new_stuff = input("Please enter an item. ")

    if new_stuff == "quit":
        print("\nHere's your list.")
        show_list()
        break

    elif new_stuff == "help":
        show_help()
        continue

    elif new_stuff == "show":   
        show_list()
        continue

    else:

        new_list = new_stuff.split(",")

        index = input("If you want to add this to a certain spot, enter the appropriate number. Or juts hit 'enter' to add it to the end of the list. Currently {} items in the list".format(len(shopping_list)))

        if index:
            spot = int(index) - 1
            for item in new_list:
                shopping_list.insert(spot, item.strip())
                spot += 1
        else:
            for item in new_list:
                shopping_list.append(item.strip())

6 Answers

Gary Gibson
Gary Gibson
5,011 Points

I didn't include it here.

Gary Gibson
Gary Gibson
5,011 Points
shopping_list = []

def show_help():
    print("\nSeparate each item with a comma.")
    print("""Type 'done' to quit, 'show' to see the curent list, 
and 'help' to get this message as a reminder.""")

def show_list():
    count = 1
    for i in shopping_list:
        print("{}: {}".format(count, i))
        count += 1

print("Enter items for your shopping list.")
show_help()

while True:
    new_stuff = input("Please enter an item. ")

    if new_stuff == "quit":
        print("\nHere's your list.")
        show_list()
        break

    elif new_stuff == "help":
        show_help()
        continue

    elif new_stuff == "show":   
        show_list()
        continue

    else:

        new_list = new_stuff.split(",")
        try:
            index = input("If you want to add this to a certain spot, enter the appropriate number. Or juts hit 'enter' to add it to the end of the list. Currently {} items in the list".format(len(shopping_list)))
        except ValueError:
            print("Please enter a number.")

        else:
            if index:
                spot = int(index) - 1
                for item in new_list:
                    shopping_list.insert(spot, item.strip())
                    spot += 1
            else:
                for item in new_list:
                    shopping_list.append(item.strip())
Brendan Whiting
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,716 Points

Here is my version:

shopping_list = []

def remove_item(idx):
  index = idx - 1
  item = shopping_list.pop(index)
  print("Remove {}.".format(item))

def show_help():
  print("\nSeparate each item with a comma.")
  print("Type DONE to quit, SHOW to see the current list, and HELP to get this message, REMOVE to delete an item")

def show_list():
  count = 1
  for item in shopping_list:
    print("{}: {}".format(count, item))
    count += 1

print("Give me a list of things you want to shop for.")
show_help()

while True:
  new_stuff = input("> ")

  if new_stuff == "DONE":
    print("\nHere's our list:")
    show_list()
    break
  elif new_stuff == "HELP":
    show_help()
    continue
  elif new_stuff == "SHOW":
    show_list()
    continue
  elif new_stuff == "REMOVE":
     idx = input("Which item? Tell me the number. ")
     remove_item(int(idx))
  else:
    new_list = new_stuff.split(",")
    index = input("Add this at a certain spot? Press enter for the end of the list, " "or give me a number. Currently {} items in the list. ".format(len(shopping_list)))
    while True:  #making a loop, so they can keep trying til they get it right
      if len(index):  ## if they didn't just hit "enter"
        try:
          int(index)   ## if index can be converted to an int, it will keep going, otherwise it raise a ValueError and jump to the except block
          spot = int(index) - 1
          for item in new_list:
              shopping_list.insert(spot, item.strip())
              spot += 1
          break ##exiting this while loop because we succeeded this task
        except ValueError:
          index = input("That wasn't a number. Try giving me a number again for a spot, or press enter for the end of the list")
          ##  in this case it's going to loop back again to line 41, test to see if they hit enter and test to see if it's an int
      else: ## if index doesn't have a length, and they just hit "enter" we put their items at the end   
        for item in new_list:
            shopping_list.append(item.strip())
        break
Gary Gibson
Gary Gibson
5,011 Points

I don't know what I did, but now this code works:

shopping_list = []

def show_help():
    print("\nSeparate each item with a comma.")
    print("""Type 'done' to quit, 'show' to see the curent list, 
and 'help' to get this message as a reminder.""")

def show_list():
    count = 1
    for i in shopping_list:
        print("{}: {}".format(count, i))
        count += 1

print("Enter items for your shopping list.")
show_help()

while True:
    new_stuff = input("Please enter an item. ")

    if new_stuff == "quit":
        print("\nHere's your list.")
        show_list()
        break

    elif new_stuff == "help":
        show_help()
        continue

    elif new_stuff == "show":   
        show_list()
        continue

    elif new_stuff == "":
        print("Nothing? Are you sure?")

    else:

        new_list = new_stuff.split(",")
        try:
            index = input("If you want to add this to a certain spot, enter the appropriate number. Or juts hit 'enter' to add it to the end of the list. Currently {} items in the list".format(len(shopping_list)))
        except ValueError:
            print("Please enter a number.")

        else:
            if index:
                spot = int(index) - 1
                for item in new_list:
                    shopping_list.insert(spot, item.strip())
                    spot += 1
            else:
                for item in new_list:
                    shopping_list.append(item.strip())