CHAPTER 9 — Strings & Text Manipulation

CHAPTER 9 — Strings & Text Manipulation - Printable Version

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CHAPTER 9 — Strings & Text Manipulation - Leejohnston - 11-15-2025

Chapter 9 — Strings & Text Manipulation
Understanding how Python handles text — joining it, slicing it, editing it, and displaying it properly.

A string is text inside quotation marks:

Code:
"Hello"

'Python'

"123"

"Lee Johnston"

Strings are everywhere:
• names
• messages
• user input
• menus
• data files
• website text

---

9.1 Creating Strings

Use single or double quotes:

Code:
message = "Welcome!"

note = 'Python is fun.'

Both work the same.

---

9.2 Multi-line Strings

Use triple quotes:

Code:
story = """

This is line one.

This is line two.

"""

---

9.3 Combining Strings (Concatenation)

Code:
first = "Lumin"

second = "Archive"

title = first + " " + second

Output:

Code:
Lumin Archive

---

9.4 Repeating Strings

Code:
print("Hi! " * 3)

Output:

Code:
Hi! Hi! Hi!

---

9.5 Getting Length of a String

Use len():

Code:
name = "Johno"

print(len(name))

Output:

Code:
5

---

9.6 Indexing (Getting a Single Character)

Strings act like sequences:

Code:
name = "Python"

print(name[0])  # P

print(name[3])  # h

Indexes start at 0.

---

9.7 Slicing (Getting Parts of a String)

Code:
word = "Harmonics"

print(word[0:4])  # Harm

print(word[4:])    # onics

Format:

Code:
string[start:end]

---

9.8 Changing Case

Code:
text = "the lumin archive"

print(text.upper())  # THE LUMIN ARCHIVE

print(text.title())  # The Lumin Archive

print(text.lower())  # the lumin archive

---

9.9 Useful String Methods

Code:
.strip()    # remove spaces

.replace()  # replace text

.startswith()

.endswith()

Examples:

Code:
msg = "  hello world  "

print(msg.strip())        # "hello world"

print(msg.replace("world", "Johno"))

---

9.10 Formatting Strings (IMPORTANT)

## Method 1 — f-strings (recommended)

Code:
name = "Lee"

score = 42

print(f"{name} scored {score} points!")

## Method 2 — format()

Code:
print("Welcome, {}!".format("Mia"))

---

9.11 Escape Characters

Use backslash for special characters:

Code:
print("He said \"Hello\" to me.")

print("Line one\nLine two")

---

9.12 Converting Types

You CANNOT add text and numbers directly.

❌ Error:

Code:
age = 20

print("Age: " + age)

✔ Fix:

Code:
print("Age: " + str(age))

---

9.13 Mini Project — Welcome Banner

Ask the user:

• name
• favourite subject

Output something like:

Code:
====================

 Welcome, Mia!

 Your favourite subject is: Science

====================

---

9.14 Challenge — Username Generator

Ask for:

• first name
• last name
• favourite number

Create a username such as:
mia_johnston_42

Rules:

• everything lowercase
• no spaces
• use underscores

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9.15 Chapter Summary

• strings store text
• indexing gets one character
• slicing gets a portion
• .upper(), .lower(), .strip(), .replace() are essential
• f-strings make formatting easy
• convert numbers to strings
• escape characters help format output

Next:
Chapter 10 — Conditions & If Statements

This is where programs start *thinking* — making decisions, choosing paths, and becoming interactive.

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Written and Compiled by Lee Johnston — Founder of The Lumin Archive