Creating and Concatenating Strings

A string is a sequence of characters enclosed in quotes. You can use single quotes 'hello' or double quotes "hello". Concatenation means joining strings together using the + operator.

# Creating strings
greeting = "Hello"
name = 'Alice'

# Concatenation (joining strings)
message = greeting + ", " + name + "!"
print(message)

# f-strings (formatted string literals) - the modern way
age = 16
print(f"My name is {name} and I am {age} years old.")
print(f"Next year I will be {age + 1}.")

Output:
Hello, Alice!
My name is Alice and I am 16 years old.
Next year I will be 17.

String Slicing and Indexing

Every character in a string has a position called an index. In Python, indexing starts at 0. You can extract parts of a string using slicing with the syntax string[start:end].

word = "Python"
#        P  y  t  h  o  n
# Index: 0  1  2  3  4  5

print(word[0])      # First character: P
print(word[-1])     # Last character: n
print(word[0:3])    # Characters 0, 1, 2: Pyt
print(word[2:])     # From index 2 to end: thon
print(word[:4])     # From start to index 3: Pyth
print(len(word))    # Length of string: 6

Output: P | n | Pyt | thon | Pyth | 6

String Methods and Escape Characters

Python strings come with many built-in methods (functions attached to the string). Escape characters start with a backslash \ and represent special characters.

text = "  Hello, World!  "

# Common string methods
print(text.strip())        # Remove whitespace: "Hello, World!"
print(text.lower())        # Lowercase: "  hello, world!  "
print(text.upper())        # Uppercase: "  HELLO, WORLD!  "
print(text.replace("World", "Python"))  # Replace text
print("hello".count("l"))  # Count occurrences: 2
print("hello".find("ll"))  # Find position: 2

# Escape characters
print("She said \"Hi!\"")   # \" for quotes inside quotes
print("Line 1\nLine 2")    # \n for new line
print("Column1\tColumn2")  # \t for tab

Key Vocabulary

Concatenation

Joining two or more strings together using the + operator.

f-string

A formatted string literal f"..." that lets you embed expressions inside {}.

Slicing

Extracting a portion of a string using string[start:end] syntax.

Escape Character

A special character starting with \ such as \n (newline) or \t (tab).

Worked Examples

1

Format a student report using f-strings

name = "Olivia"
subject = "Mathematics"
score = 87.5

report = f"Student: {name}\nSubject: {subject}\nScore: {score}%"
print(report)
print(f"Grade: {'Distinction' if score >= 85 else 'Credit'}")

Step 1: We store the student's details in variables.

Step 2: The f-string lets us embed variables directly inside {} and use \n for line breaks.

Output: Student: Olivia | Subject: Mathematics | Score: 87.5% | Grade: Distinction

2

Extract initials from a full name using slicing

full_name = "Sarah Jane Smith"
parts = full_name.split()     # Split into a list: ["Sarah", "Jane", "Smith"]

first_initial = parts[0][0]   # "S"
middle_initial = parts[1][0]  # "J"
last_initial = parts[2][0]    # "S"

initials = first_initial + middle_initial + last_initial
print(f"Initials: {initials}")  # Initials: SJS

Step 1: split() breaks the string into a list of words.

Step 2: We use [0] on each word to get the first character, then concatenate them.

3

Clean and format user input

raw_email = "  [email protected]  "

# Clean the email
clean_email = raw_email.strip().lower()
print(f"Cleaned email: {clean_email}")

# Check the domain
domain = clean_email.split("@")[1]
print(f"Domain: {domain}")
print(f"Is Gmail? {domain == 'gmail.com'}")

Step 1: strip() removes whitespace, and lower() converts to lowercase.

Step 2: We split at @ and take the second part [1] to get the domain.

Output: Cleaned email: [email protected] | Domain: example.com | Is Gmail? False

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

What does "Python"[1] return?

"y" "P" "Py" "t"

Question 2

What does "HELLO".lower() return?

"HELLO" "hello" "Hello" Error

Question 3

Given name = "Alice", what does f"Hi {name}!" produce?

"Hi {name}!" "f Hi Alice!" "Hi Alice!" Error

Question 4

What does "Hello World"[0:5] return?

"World" "Hello " "Hell" "Hello"

Question 5

What escape character creates a new line?

\n \t \\ \"

Python Strings