CODEWITHSUNDEEP
pythonstringfor-loopwhile-loop
lilai
lilai

Reputation: 39

Checking if string is in a list of strings using loop

I have a function that checks if a given string is in a list of strings using a for and while loop. I’m not supposed to use the ‘in’ operator. Here’s my code using a for loop:

def word_in_list(words, word):
    for strings in words:
        if len(words) > 0 and strings == word:
            return True
        else:
            return False

However, it is not returning True unless the single string is the first element of the list. The list should return False in case the list is empty. And how can I solve the same problem using a while loop (and without 'in' operator)?

Upvotes: 0

Views: 5163

Answers (4)

lllrnr101
lllrnr101

Reputation: 2343

Your else block kicks-in without finishing the iteration on complete list.

def word_in_list(list_of_words, word_to_search):
    found = False
    for word in list_of_words:
        if word == word_to_search:
            found = True
            break # breaks iff the word is found
    return found

Any particular reason you are adamant not to use the 'in' operator? Also, please be careful about the indentation in the code you paste.

Upvotes: 0

Samandar
Samandar

Reputation: 64

simly use this code

def word_in_list(words, word):
    if word in words:
       return True
    else
       return False

Upvotes: 0

Jarvis
Jarvis

Reputation: 8564

Don’t return False the moment you find one mismatch, return False when you are done checking all possibilities and not finding any match:

def word_in_list(words, word):
    for strings in words:
        if strings == word:
            return True
    return False

Also, no need to check the length of list every time, if it's zero, you don't run the loop at all and directly return False.

Upvotes: 1

Daniel
Daniel

Reputation: 485

Your code is wrong because of the else statement. Your function must return False only after checking the whole list, not just the first element. Whenever a function gets to a "return" instruction, it stops, so it just checked the first one. This is the correct solution:

def word_in_list(words, word):
    i = 0
    while i < len(words):
        if words[i] == word:
            return True
        i += 1
    return False

Upvotes: 0

Related Questions