Python simple check

Question

I am just learning Python and I want to check if a list contains a word. When I check for the word it always returns 0, even though the function can find it and print it. But the if/else statement always return 0, when I use 2 returns as below. Can you help me?

def line_number(text, word):
    """
    Returns the line number (beginning with 1) where the word appears for the first time
    :param text: Text in which the word is searched for
    :param word: A word to search for
    :return: List of Line Numbers
    """
    lines = text.splitlines()
    i = 0
    for line in lines:
        i = i +1
        if word in line:
            return i
        else:
            return 0
            # print("nope")


words = ['erwachet', 'Brust', 'Wie', 'Ozean', 'Knabe']
    for word in words:
        num = line_number(wilhelm_tell, word)
        if num > 0:
            print(f"Das Word {word} findet sich auf Zeile {num}.")
        else:
            print(f"Das Wort {word} wurde nicht gefunden!")

In your first loop iteration it has to return something according to your logic. Ask yourself why are you returning immediately 0 if you can't find the word. — BcK
– BcK, Commented Mar 16, 2021 at 21:50
Ask yourself, what happens if the first line of Guglielmo Tell doesn't contain word? — gboffi
– gboffi, Commented Mar 16, 2021 at 21:53

Sebastian Borquez Gonzalez · Accepted Answer · 2021-03-16 22:06:52Z

2

You should return 0 after the for loop ends and not inside the loop.

def line_number(text, word):
    """
    Returns the line number (beginning with 1) where the word appears for the first time
    :param text: Text in which the word is searched for
    :param word: A word to search for
    :return: List of Line Numbers
    """
    lines = text.splitlines()
    i = 0
    for line in lines:
        i = i +1
        if word in line:
            return i
    return 0

The problem is the else statement inside the loop because it will break the loop in the first iteration.

answered Mar 16, 2021 at 22:06

Sebastian Borquez Gonzalez

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1 Comment

Luis Michael Luethi Over a year ago

thanks alot. I overthought the whole if/else loop. the loop will end on the first find, if its true

Eichelbart · Accepted Answer · 2021-03-16 22:04:55Z

2

I think the problem is that you're returning 0 on the first line the word is not in. So instead, you should return 0 after you looked through every line:

def line_number(text, word):
    """
    Returns the line number (beginning with 1) where the word appears for the first time
    :param text: Text in which the word is searched for
    :param word: A word to search for
    :return: List of Line Numbers
    """
    lines = text.splitlines()
    i = 0
    for line in lines:
        i = i +1
        if word in line:
            return i
    return 0

answered Mar 16, 2021 at 22:04

Eichelbart

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Comments

Jorge Alvarado · Accepted Answer · 2021-03-16 22:07:53Z

I think the problem might be that you are returning 0 if the word is not within a line. When you use the return keyword, it will exit the function and return the value. So if a word is not within the first line of the text, it will return 0 (even though the word is present on further lines)

Here is a little example of what i think is happening:

def is_element_within_list(element_to_search, some_list):
    for element in some_list:
        if element == element_to_search:
            return True
        else:
            return False


some_list = [1, 2, 3]
element_to_search = 2
print(is_element_within_list(element_to_search, some_list))
# output: False

We have a function that checks if an element is within a list (we could use the keyword "in", but is for the sake of the example). So, despite that 2 is within some_list, the function output is False, because the function is returning False on the else if the elements are no the same

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