try/except error

That's not going to work as well as you think. You're essentially telling the computer to try to see if there's a value for index, not try to see if there's a value error.

So 3 things that will apparently happen if you run your code:

1) You don't enter anything for index. It'll read your try block, check there's no index, and run your else block appending your list to the end of the list. So if this is the case, your code will run fine.

2) You enter a non-integer value as your index. It'll read your try block, see that there's an index, try subtracting it from 1, which won't work, and then run your except ValueError block. In this case, your code will also work fine.

3) You enter an actual integer into for your index. It's going to run your try block, see there's an index, and apply your list to that spot based on your index. AND THEN it's going to read your else block, appending it again to the end of your list.

Try this code instead:

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)))

    if index:
        try:
            spot = int(index) - 1
        except ValueError:
            print("That's not a number!")
            continue

        else:  
            for item in new_list:
                shopping_list.insert(spot, item.strip()) #strip removes the white space
                spot += 1 
    else:
        for item in new_list:
            shopping_list.append(item.strip())

Now what I don't understand is, for her code:

1) Why does it still work despite not having a "Continue" in the Except block? Shouldn't it theoretically just print "That's not a number." and then run the else block?

2) Is there any reason to always have an else block after a try/except block? It seems to work with or without it.

So looks like I answered my own question. Having an except block in addition to the try/except block is dependent on if you have a continue in the exception block. If you don't have a continue, you want an else block - otherwise, it'll print out the exception message and then run whatever is next. If you include the else block, there's no need to have a continue in the exception block. For example:

1) Example of having a "continue" but no else block.

    if index:
        try:
            spot = int(index) - 1
        except ValueError:
            print("That's not a number!")
            continue
        for item in new_list:
                shopping_list.insert(spot, item.strip()) #strip removes the white space
                spot += 1 

2) Example of having no "continue", but an else block.

    if index:
        try:
            spot = int(index) - 1
        except ValueError:
            print("That's not a number!")
        else:
            for item in new_list:
                shopping_list.insert(spot, item.strip()) #strip removes the white space
                spot += 1 

It's interesting to note that else blocks in Try/Except blocks run a little different than else's in "if" blocks. In the latter, else will only run if any of the "if" blocks don't trigger. However in the former, the "else" block will trigger even if the "try" triggers (but it won't trigger if the except block triggers). The best way for me to understand it is to view the "except" block as an "if" block. Hope that helps and wasn't too confusing.

I figured it out.

        index = input("Add this at a certain spot? Pres enter for the end of the list, \n or give me a number. Currently {} items in the list.".format(len(shopping_list)))

        #~ put try above index if statement
        try:
            if index:
                spot = int(index) - 1
                for item in new_list:
                    shopping_list.insert(spot, item.strip())
                    spot += 1
        #~ except goes directly after   
        except ValueError:
            print("Please use a number")

        else:
            for item in new_list:
                shopping_list.append(item.strip())