String values and text handling in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a string in Python?

A string is a sequence of characters enclosed in quotes, used to represent text.

beginner

How do you create a multi-line string in Python?

Use triple quotes (''' or """) to create a string that spans multiple lines.

beginner

What does the len() function do when used with a string?

It returns the number of characters in the string, including spaces and punctuation.

beginner

How can you combine two strings in Python?

By using the + operator to join them together, called concatenation.

intermediate

What is the purpose of the strip() method on a string?

It removes any spaces or specified characters from the start and end of the string.

Which of these is the correct way to create a string in Python?

A text = Hello

B text = "Hello"

C text = 'Hello

D text = (Hello)

Strings must be enclosed in matching quotes, like double quotes "Hello" or single quotes 'Hello'.

What will len('Hi there') return?

A 7

B 6

C 8

D 9

The string 'Hi there' has 8 characters including the space.

What does 'Hello'.upper() do?

A Returns the length of 'Hello'

B Converts 'Hello' to 'hello'

C Removes spaces from 'Hello'

D Converts 'Hello' to 'HELLO'

The upper() method changes all letters in the string to uppercase.

How do you join two strings, 'Good' and 'Morning', with a space in between?

A 'Good' + ' ' + 'Morning'

B 'Good' . 'Morning'

C 'Good' & 'Morning'

D 'Good' - 'Morning'

Use the + operator and add a space string ' ' between the two strings.

What does ' hello '.strip() return?

A 'hello'

B ' hello '

C 'hello '

D ' hello'

strip() removes spaces from both the start and end of the string.

Explain how to create and manipulate strings in Python.

Think about how you write text and change it in Python.

Describe the difference between single, double, and triple quotes in Python strings.

Consider how you write short vs long text blocks.

Practice

1. What is the correct way to create a string in Python?

easy

A. Using quotes like "Hello" or 'Hello'

B. Using parentheses like (Hello)

C. Using curly braces like {Hello}

D. Using square brackets like [Hello]

Solution

1. Step 1: Understand string syntax in Python

   Strings are text and must be enclosed in quotes, either single or double.

2. Step 2: Check each option

   Only Using quotes like "Hello" or 'Hello' uses quotes correctly. Parentheses, curly braces, and square brackets are for other data types.

3. Final Answer:

   Using quotes like "Hello" or 'Hello' -> Option A

4. Quick Check:

   Strings need quotes = C [OK]

Hint: Remember: strings always need quotes around text [OK]

Common Mistakes:

• Using parentheses instead of quotes
• Confusing brackets with quotes
• Forgetting to close quotes

2. Which of the following is the correct syntax to create a multi-line string in Python?

easy

A. '''This is a multi-line string'''

B. "This is a multi-line string"

C. 'This is a multi-line string'

D. --This is a multi-line string--

Solution

1. Step 1: Recall multi-line string syntax

   Python uses triple quotes (either ''' or """) to create strings that span multiple lines.

2. Step 2: Evaluate options

   '''This is a multi-line string''' uses triple single quotes correctly. Options B and C use single or double quotes for single-line strings. --This is a multi-line string-- is invalid syntax.

3. Final Answer:

   '''This is a multi-line string''' -> Option A

4. Quick Check:

   Triple quotes = multi-line string [OK]

Hint: Use triple quotes for multi-line strings [OK]

Common Mistakes:

• Using single or double quotes for multi-line text
• Using invalid symbols like --
• Not closing triple quotes properly

3. What will be the output of the following code?

text = "Hello World"
print(text[6:])

medium

A. Hello

B. World

C. World!

D. Hello World

Solution

1. Step 1: Understand string slicing

   text[6:] means start from index 6 to the end of the string. Indexing starts at 0.

2. Step 2: Identify substring from index 6

   In "Hello World", index 6 is 'W', so text[6:] is "World".

3. Final Answer:

   World -> Option B

4. Quick Check:

   text[6:] = World [OK]

Hint: Remember string index starts at 0; slice from index 6 to end [OK]

Common Mistakes:

• Confusing index start point
• Including extra characters like '!'
• Printing entire string instead of slice

4. Find the error in this code snippet:

name = 'Alice
print(name)

medium

A. Incorrect use of newline character

B. print() function is misspelled

C. Missing closing quote for the string

D. Variable name is invalid

Solution

1. Step 1: Check string syntax

   The string starts with a single quote but does not have a closing quote before the newline.

2. Step 2: Identify syntax error

   Because the closing quote is missing, Python will raise a syntax error.

3. Final Answer:

   Missing closing quote for the string -> Option C

4. Quick Check:

   Unclosed string causes syntax error [OK]

Hint: Always close your quotes before newline or end [OK]

Common Mistakes:

• Forgetting to close quotes
• Thinking newline character causes error
• Assuming print is misspelled

5. You have a list of words: words = ['apple', 'banana', 'cherry']. Which code correctly joins them into a single string separated by commas?

hard

A. result = ','.join([words])

B. result = words.join(',')

C. result = ','.join('words')

D. result = ','.join(words)

Solution

1. Step 1: Understand join() method usage

   The join() method is called on the string separator and takes an iterable of strings as argument.

2. Step 2: Check each option

   result = ','.join(words) correctly calls join on the comma string with the list words. Others misuse join or pass wrong arguments.

3. Final Answer:

   result = ','.join(words) -> Option D

4. Quick Check:

   Separator.join(list) joins list items [OK]

Hint: Call join on separator string, pass list to join() [OK]

Common Mistakes:

• Calling join on the list instead of the string
• Passing string 'words' instead of list variable
• Passing list inside another list