How to add elements to the already existing elements instead of overwriting them in a list?

Question

I have this code here:

def alist():
    wor = []
    definition = []
    wele = str(input("Enter a word: "))
    dele = str(input("Enter a definition: "))
    x = wor.append(wele)
    y = def.append(dele)
    print("Words' List: ", wor, "\nDefinitions' List: ", definition)

Whenever I run it, I can add elements to the lists wor and def, however, whenever I run it again, it overwrites the elements I added earlier when I ran it the first time. I have avoided this problem by turning wor and def into global variables. Is there any other method other than making the two lists into global variables?

Thanks!

Answer 1

You're creating new, empty lists each time you call the function. The function should take the lists as parameters and modify them.

def alist(wlist, dlist):
    wele = input("Enter a word: ")
    dele = input("Enter a definition: ")
    wlist.append(wele)
    dlist.append(dele)

word_list = []
def_list = []

word_count = int(input("How many words are you defining? "))
for _ in range(word_count):
    alist(word_list, def_list)
print("Words' List: ", word_list, "\nDefinitions' List: ", def_list)

Making the lists parameters allows you to have multiple word lists, e.g.

spanish_words = []
spanish_defs = []
alist(spanish_words, spanish_defs)

However, it's generally poor design to keep related data in separate lists, which you have to keep in sync. It would be better to use a single list of dictionaries or tuples, so all the related items (e.g. the word and its definition) are together.