String length and membership test in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of string length and membership test

What is the output of this Python code?

Python

s = "hello world"
result = len(s) > 5 and 'w' in s
print(result)

A False

B TypeError

C SyntaxError

D True

💡 Hint

Check if the string length is greater than 5 and if the character 'w' is inside the string.

The string 'hello world' has length 11, which is greater than 5, and it contains the character 'w'. So both conditions are True, making the result True.

❓ Predict Output

intermediate

Check membership and length in a string

What will be printed by this code?

Python

text = "Python3.12"
output = ('3' in text) and (len(text) == 9)
print(output)

A NameError

B True

C False

D IndexError

💡 Hint

Check if '3' is in the string and if the length equals 9.

The string 'Python3.12' contains '3' but its length is 10, not 9, so the expression evaluates to False.

❓ Predict Output

advanced

Result of combined string length and membership test

What is the output of this code snippet?

Python

s = "DataScience"
result = (len(s) < 10) or ('a' not in s)
print(result)

A False

B True

C SyntaxError

D TypeError

💡 Hint

Evaluate both conditions and then the or operation.

The length of 'DataScience' is 11, so len(s) < 10 is False. The character 'a' is in the string, so 'a' not in s is False. False or False is False.

❓ Predict Output

advanced

Output of membership test with string length check

What does this code print?

Python

word = "challenge"
print(len(word) == 9 and 'z' in word)

A False

B True

C SyntaxError

D IndexError

💡 Hint

Check the length and if 'z' is in the string.

The length of 'challenge' is 9, so len(word) == 9 is True. But 'z' is not in the string, so 'z' in word is False. True and False is False.

🧠 Conceptual

expert

Understanding string membership and length logic

Given the code below, what is the value of variable result after execution?

Python

text = "OpenAI GPT"
result = (len(text) != 10) and (' ' in text) and ('A' in text)

A True

B False

C TypeError

D NameError

💡 Hint

Check each condition carefully and combine with 'and'.

The string 'OpenAI GPT' has length 10, so len(text) != 10 is False. Since the first condition is False, the whole 'and' expression is False regardless of the others.

Practice

1.

What does the expression len('hello') return in Python?

easy

A. 5

B. 'hello'

C. 4

D. Error

Solution

1. Step 1: Understand the len() function

   The len() function counts how many characters are in a string.

2. Step 2: Count characters in 'hello'

   The word 'hello' has 5 letters: h, e, l, l, o.

3. Final Answer:

   5 -> Option A

4. Quick Check:

   len('hello') = 5 [OK]

Hint: Count letters to find length quickly [OK]

Common Mistakes:

• Counting letters incorrectly
• Confusing len() with printing string
• Expecting len() to return string itself

2.

Which of the following is the correct syntax to check if the letter 'a' is in the string word?

easy

A. word.contains('a')

B. word in 'a'

C. in 'a' word

D. 'a' in word

Solution

1. Step 1: Recall Python membership syntax

   To check if a substring is inside a string, use substring in string.

2. Step 2: Apply to letter 'a' and variable word

   We write 'a' in word to check if 'a' is inside word.

3. Final Answer:

   'a' in word -> Option D

4. Quick Check:

   Use 'in' as: substring in string [OK]

Hint: Use 'in' with substring first, then string [OK]

Common Mistakes:

• Reversing order of 'in'
• Using non-Python syntax like contains()
• Syntax errors with 'in' placement

3.

What is the output of this code?

word = 'python'
print(len(word) > 5 and 'y' in word)

medium

A. False

B. 6

C. True

D. Error

Solution

1. Step 1: Calculate len(word)

   The string 'python' has 6 characters, so len(word) is 6.

2. Step 2: Evaluate conditions

   Check if 6 > 5 (True) and if 'y' is in 'python' (True). Both are True, so the whole expression is True.

3. Final Answer:

   True -> Option C

4. Quick Check:

   len(word)>5 and 'y' in word = True [OK]

Hint: Check length first, then membership with 'and' [OK]

Common Mistakes:

• Confusing > with >= operator
• Forgetting 'and' logic
• Miscounting string length

4.

Find the error in this code snippet:

text = 'apple'
if 'p' not in text:
    print('No p found')
else
    print('p is present')

medium

A. Missing colon ':' after else

B. Wrong use of 'not in' operator

C. Variable 'text' is not defined

D. Indentation error on print statements

Solution

1. Step 1: Check syntax of if-else

   Python requires a colon ':' after both if and else statements.

2. Step 2: Identify missing colon

   The else line is missing a colon at the end, causing a syntax error.

3. Final Answer:

   Missing colon ':' after else -> Option A

4. Quick Check:

   else: needs colon [OK]

Hint: Always put ':' after else and if lines [OK]

Common Mistakes:

• Omitting colon after else
• Misusing 'not in' operator
• Incorrect indentation

5.

Given a list of words, write a Python expression to create a new list containing only words longer than 4 characters and containing the letter 'e'.

Which of these is correct?

hard

A. [w for w in words if len(w) > 4 or 'e' in w]

B. [w for w in words if len(w) > 4 and 'e' in w]

C. [w for w in words if len(w) >= 4 and 'e' not in w]

D. [w for w in words if len(w) < 4 or 'e' not in w]

Solution

1. Step 1: Understand the conditions

   We want words longer than 4 characters and that contain 'e'. This means length > 4 and 'e' in word.

2. Step 2: Check list comprehension syntax

   The correct syntax is [w for w in words if len(w) > 4 and 'e' in w] which filters words by both conditions.

3. Final Answer:

   [w for w in words if len(w) > 4 and 'e' in w] -> Option B

4. Quick Check:

   Filter with len()>4 and 'e' in word [OK]

Hint: Use 'and' to combine length and membership tests [OK]

Common Mistakes:

• Using 'or' instead of 'and'
• Wrong comparison operators
• Negating membership incorrectly