Strings

Strings are sequences of characters enclosed in quotes. They are immutable. Python supports single, double, and triple quotes.

Indexing & Slicing

Access characters by index: s[0] is the first character, s[-1] is the last. Slice with s[1:4].

Common Methods

• .upper(), .lower() � change case
• .strip() � remove whitespace
• .split(), .replace(), .find()

F-Strings

Use f"Hello, {name}!" to embed expressions.

Syntax

PYTHON

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s = "Hello, World!"
print(s[0])       # H
print(s[-1])      # !
print(s[0:5])     # Hello
print(s.upper())
print(s.split(", "))

name = "Alice"
print(f"Hello, {name}!")

Python Strings

PYTHON

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text = "Hello, SukhNexus!"

print("Length:", len(text))
print("Upper:", text.upper())
print("Lower:", text.lower())
print("Title:", text.title())

# Slicing
print("Slice:", text[0:5])
print("From 7:", text[7:])
print("Reversed:", text[::-1])

# Methods
print("Count:", text.count("S"))
print("Find:", text.find("Sukh"))
print("Replace:", text.replace("Hello", "Hi"))
print("Split:", text.split(","))

# f-strings
name = "Alice"
score = 95.5
print(f"{name} scored {score:.1f}%")

Try It Yourself

Practice

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Exercise

Reverse a string using slicing.

Answer

text = "Hello"
print(text[::-1])  # olleH

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Exercise

Format a product line with f-string.

Answer

print(f"Item: Widget, Qty: 5, Total: ${5 * 9.99:.2f}")

Quick Quiz

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What does "Python"[-1] return?

P

n

Error

Negative indexing returns the last character, "n".

Retry Quiz

Interview Questions

Why are strings immutable in Python?

Immutability enables dictionary keys, thread safety, and memory optimization through string interning.

Next Lesson

Numbers