'Find one character in a string of any number of characters and return True or False

I'm having trouble returning the correct Boolean value back after checking for all occurrences of a single letter in a string of any length. If the single letter is in the string, I want it to return True. If the single letter is not in the string, I want it to return False. However, when I run it in python, it is just returning back only True or only False and is not accurately checking if the single letter is in the word.

def contains_char(any_length: str, single_character: str) -> bool:
    """A way to find one character in a word of any length."""
    assert len(single_character) == 1
    any_length = ""
    single_character = ""
    check_character: bool = False
    i: int = 0 
    while i < len(any_length):
        if any_length[i] == single_character[0]:
            check_character is True
        else:
            i += 1
            alternative_char: int = 0
            while check_character is not True and i < len(any_length):
                if any_length[alternative_char] == single_character[0]:
                    check_character == True
                else:
                    alternative_char += 1
    if check_character is not False:
        return False
    else:
        return True

python

Solution 1:^[1]

in keyword uses linear search and returns boolean value O(n).

def contains_char(any_length: str, single_character: str) -> bool:
    return single_character in str

Linear search follows

def contains_char(any_length: str, single_character: str) -> bool:
    # For each loop iterates through each character in string
    for char in str:
        if char == str:
            return True
    return False

Solution 2:^[2]

Maybe I'm missing something but Python's in operator does this out the box.

if single_character in any_length:
    return True
else:
    return False

Solution 3:^[3]

you are making another mistake in the start of the function:

any_length = ""

after you change the value of any_length your function will never work

Solution 4:^[4]

in Does this for you:

def char_in_word(word, char):
    return char in word

However if you don't want to use builtin, use this:

def char_in(word, char):
    for i in word:
        if i == char:
            return True
    return False

Solution 5:^[5]

def contains_char(string,character):
    if character in string:
        return True 
    return False

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1
Solution 2	Karim Tabet
Solution 3	yotamolenik
Solution 4
Solution 5	keineahnung2345

'Find one character in a string of any number of characters and return True or False

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]