why is my python code outputting the wrong thing?

Question

words=[]
word=input("Word:")
count=0
while word != '':
 count+=1
 words.append(word) 
 word=input("Word:")
 for w in words:
 if words.count(w)>1:
 count-=1 
print("You know",count,"unique word(s)")

So what my code does is, it allows the user to input words and then checks to see if they have any duplicate words; if they do, it doesn't count. So after that's done it tells you how many 'unique words' you know.

The problem is: when there are no duplicates it outputs the right amount of 'unique words' however when there are duplicates it outputs the 'right amount of unique words' - 1. So let's say i give in 3 words and 2 of them are duplicates; it will say there's only 1 unique word. Thank you for any help.

Answer 1

It might help to understand what's going on if you add print(words) after words.append(word).

What happens is that word gets added as a new item to the array. In the loop where you decrement count you decrement for each word that is not unique, i.e. if a word occurs twice you decrement twice.

Input words count
a [a] 1
a, b [a, b] 2
a, b, b [a, b, b] 1
a, b, b, b [a, b, b, b] -1
a, b, b, c, c [a, b, b, c, c] -3

Another problem is that the for-loop happens after each input, i.e. you decrement the same duplicate multiple times.

A fixed version of your program that keeps inputing individual words would be

words=[]
word=input("Word:")
while word != '':
 words.append(word)
 word=input("Word:")
uniquewords = set(words)
print("You know",len(uniquewords),"unique word(s)")

• Animedragon: Thank you for taking your time to answer my question, thank you to the other person who helped as well, it was much appreciated.

Answer 2

You can split the user's input on a space and then add the item into a set instead. A set contains unique items, so adding "a" to it three times would result in only containing one "a".

word = input('Word:')
split_word = word.split() # splits on space
set_word = set(split_word) # turns the list into a set
unique_words = len(set_word)
print("You know",unique_words,"unique word(s)")