String creation and representation in Python

Introduction

Strings let us store and show words or sentences in programs. They help us work with text like names, messages, or any letters.

When you want to save a person's name in your program.

When you need to display a message to the user.

When you want to store a sentence or paragraph.

When you need to keep track of any text data like addresses or emails.

Syntax

Python

string_variable = 'Hello, world!'
string_variable = "Hello, world!"
string_variable = '''This is a
multi-line string.'''
string_variable = """This is also a
multi-line string."""

You can use single quotes (' ') or double quotes (" ") to create strings.

Triple quotes (''' ''' or """ """) let you write strings that span multiple lines.

Examples

A simple string using single quotes.

Python

greeting = 'Hi there!'
print(greeting)

Using double quotes and escaping inner quotes with backslash.

Python

quote = "She said, \"Hello!\""
print(quote)

A multi-line string using triple single quotes.

Python

multi_line = '''This is line one.
This is line two.'''
print(multi_line)

A multi-line string using triple double quotes.

Python

multi_line2 = """Line one.
Line two."""
print(multi_line2)

Sample Program

This program creates strings using single quotes and triple quotes. It also shows how to insert a variable inside a string using f-strings.

Python

name = 'Alice'
welcome_message = f"Hello, {name}! Welcome to the program."
print(welcome_message)

multi_line_text = '''This program shows how strings work.
You can write text in many ways.'''
print(multi_line_text)

Important Notes

Remember to use backslash (\) to include special characters like quotes inside strings.

Strings are always inside quotes, so forgetting them causes errors.

Triple quotes are great for writing long text or notes inside your code.

Summary

Strings store text inside quotes.

Use single, double, or triple quotes depending on your needs.

Triple quotes help write multi-line text easily.

Practice

1. Which of the following is a correct way to create a string in Python?

easy

A. text = Hello'

B. text = Hello

C. text = 'Hello'

D. text = """Hello

Solution

1. Step 1: Check string delimiters

   Python strings must be enclosed in matching quotes: single ('') or double (\"\").

2. Step 2: Validate each option

   text = 'Hello' uses single quotes correctly. text = Hello misses quotes. text = Hello' has mismatched quotes. text = """Hello has unclosed triple quotes.

3. Final Answer:

   text = 'Hello' -> Option C

4. Quick Check:

   Strings need matching quotes = A [OK]

Hint: Strings always need matching quotes around text [OK]

Common Mistakes:

• Forgetting quotes around text
• Using mismatched quotes
• Leaving quotes unclosed

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

easy

A. text = '''Hello
World'''

B. text = "Hello\nWorld"

C. text = 'Hello\nWorld'

D. text = '''Hello\nWorld'''

Solution

1. Step 1: Understand multi-line string syntax

   Triple quotes (''' or """) allow writing strings across multiple lines without escape characters.

2. Step 2: Analyze options

   Options A and B use single/double quotes with escaped newline, which works but is not multi-line string creation. text = '''Hello\nWorld''' uses triple quotes but escapes newline, so it shows literal \n. text = '''Hello World''' uses triple quotes with actual newline, creating a true multi-line string.

3. Final Answer:

   text = '''Hello World''' -> Option A

4. Quick Check:

   Triple quotes with real newlines = C [OK]

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

Common Mistakes:

• Using single or double quotes for multi-line text
• Escaping newlines inside triple quotes
• Confusing escaped \n with actual newlines

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

text = '''Hello
World'''
print(text)

medium

A. Hello\nWorld

B. Hello
World

C. Hello World

D. SyntaxError

Solution

1. Step 1: Understand triple-quoted string behavior

   Triple quotes preserve newlines inside the string as actual line breaks.

2. Step 2: Analyze the string content and print output

   The \n escape sequence in the triple-quoted string is interpreted as a newline character, so the string content is 'Hello' + newline + 'World'. Thus, print(text) outputs two lines: 'Hello' then 'World' on the next line.

3. Final Answer:

   Hello World (two lines) -> Option B

4. Quick Check:

   Triple quotes keep newlines = A [OK]

Hint: Triple quotes print newlines as line breaks, not \n text [OK]

Common Mistakes:

• Confusing escaped \n with actual newline
• Expecting literal \n to print as two characters
• Thinking triple quotes cause syntax error

4. The following code throws an error. What is the problem?

text = 'It's a sunny day'

medium

A. Missing escape for single quote inside string

B. Using double quotes instead of single quotes

C. Triple quotes needed for single quotes inside

D. No error, code is correct

Solution

1. Step 1: Identify the string delimiter and content

   The string uses single quotes to start and end, but contains an unescaped single quote inside (in "It's").

2. Step 2: Understand why error occurs

   The inner single quote ends the string early, causing a syntax error. It needs to be escaped with a backslash or use double/triple quotes.

3. Final Answer:

   Missing escape for single quote inside string -> Option A

4. Quick Check:

   Escape inner quotes or use different quotes = D [OK]

Hint: Escape inner quotes or use different quote types [OK]

Common Mistakes:

• Ignoring escape for inner quotes
• Assuming single quotes inside single quotes are allowed
• Not using triple quotes for complex strings

5. You want to create a dictionary where keys are words and values are their lengths from a multi-line string. Which code correctly creates this dictionary?

text = '''apple\nbanana\ncherry\n'''
# Fill in the blank:
d = {word: len(word) for word in _____}

hard

A. text.split()

B. text.split(' ')

C. text.split('\n')

D. text.splitlines()

Solution

1. Step 1: Understand the string and splitting methods

   The string ends with a newline ('''apple\nbanana\ncherry\n'''). splitlines() and split('\n') include a trailing empty string ''. split() splits on all whitespace (including newlines) and discards empty fields. split(' ') ignores newlines.

2. Step 2: Choose the method that avoids extra empty key

   split() produces exactly {'apple':5, 'banana':6, 'cherry':6} without '' : 0.

3. Final Answer:

   text.splitlines() -> Option D

4. Quick Check:

   splitlines() handles newlines cleanly = B [OK]

Hint: Use splitlines() to split on newlines cleanly [OK]

Common Mistakes:

• Using split() which discards empty lines but may split on other whitespace
• Using split('\n') which includes trailing empty string
• Using split(' ') which misses newlines