Formatting Strings

Table of Contents

1. Formatting Strings – Adjusting Case
2. Formatting Strings – Adding and Removing Spaces
3. Formatting Strings – Finding and Replacing Substrings
4. Formatting Strings – Splitting
5. Formatting Strings – Partitioning Strings
6. Tasks

1. Formatting Strings – Adjusting Case

1.1 Convert to Uppercase:

text = "hello"
print(text.upper())  # Output: "HELLO"

1.2 Convert to Lowercase:

text = "HELLO"
print(text.lower())  # Output: "hello"

1.3 Capitalize First Letter:

text = "python is fun"
print(text.capitalize())  # Output: "Python is fun"

1.4 Title Case (First letter of each word capitalized):

text = "hello world"
print(text.title())  # Output: "Hello World"

1.5 Swap Case:

text = "PyTHon"
print(text.swapcase())  # Output: "pYthON"

2. Formatting Strings – Adding and Removing Spaces

1. Removing Extra Spaces:

• Remove leading and trailing spaces:

text = "   hello world   "
print(text.strip())  # Output: "hello world"

• Remove only leading spaces:

text = "   hello"
print(text.lstrip())  # Output: "hello"

• Remove only trailing spaces:

text = "hello   "
print(text.rstrip())  # Output: "hello"

2. Adding Spaces or Padding:

• Center-align with padding:

text = "Python"
print(text.center(10))  # Output: "  Python  "

• Left-align:

print(text.ljust(10))  # Output: "Python    "

• Right-align:

print(text.rjust(10))  # Output: "    Python"

Tasks

Task 1: String Info

Write a program that asks the user for their name and prints:

• The name in all uppercase
• The name in all lowercase
• The number of characters in the name

Example:

# Sample output for name "Alice"
Uppercase: ALICE  
Lowercase: alice  
Length: 5

Task 2: Remove Extra Spaces

Given a string with extra spaces:

sentence = "   Python is fun!   "

Write code to:

• Remove the spaces
• Print the cleaned-up sentence

Task 3: Align a String

Print the word "Code":

• Centered in a 20-character space
• Left-aligned in a 20-character space
• Right-aligned in a 20-character space

3. Formatting Strings – Finding and Replacing Substrings

🔹 find() Method

• Returns the index of the first occurrence of a substring.
• Returns -1 if not found.

text = "Hello, welcome to Python!"
position = text.find("welcome")
print(position)  # Output: 7

🔹 replace() Method

• Replaces all occurrences of a substring with another substring.

text = "I love Python. Python is awesome!"
new_text = text.replace("Python", "coding")
print(new_text)
# Output: I love coding. coding is awesome!

🔹 Example: Censoring Words

comment = "This product is bad, really bad!"
cleaned = comment.replace("bad", "***")
print(cleaned)
# Output: This product is ***, really ***!

4. Formatting Strings – Splitting

🔹 split() Method

• Splits a string into a list based on a separator.

• When you use split() without any arguments, it splits the string using any whitespace as the separator. This includes:

  • Spaces (" ")
  • Tabs ("\t")
  • Newlines ("\n")

Also, it automatically removes extra spaces, so multiple spaces are treated as one.

📌 Syntax

string.split()

✅ Examples

1. Basic Usage

sentence = "Python is fun"
words = sentence.split()
print(words)
# Output: ['Python', 'is', 'fun']

2. With Extra Spaces

sentence = "   Python    is   powerful   "
words = sentence.split()
print(words)
# Output: ['Python', 'is', 'powerful']

3. With Tabs and Newlines

text = "Learn\tPython\nNow"
parts = text.split()
print(parts)
# Output: ['Learn', 'Python', 'Now']

🔹 Splitting by a Custom Separator

data = "apple,banana,orange"
fruits = data.split(",")
print(fruits)
# Output: ['apple', 'banana', 'orange']

🔹 Example: Extracting Names from a CSV Line

csv_line = "John,Doe,25"
parts = csv_line.split(",")
print("First Name:", parts[0])
print("Last Name:", parts[1])

5. Formatting Strings – Partitioning Strings

🔹 partition() Method

• Splits the string at the first occurrence of the separator.
• Returns a tuple: (before, separator, after)

email = "username@example.com"
result = email.partition("@")
print(result)
# Output: ('username', '@', 'example.com')

🔹 Handling Missing Separator

text = "hello world"
result = text.partition(":")
print(result)
# Output: ('hello world', '', '')

🔹 Example: Extracting Domain from an Email

email = "jane.doe@gmail.com"
_, _, domain = email.partition("@")
print("Domain:", domain)
# Output: Domain: gmail.com

✅ Summary Table

6. Tasks

✅ Tasks: find() and replace()

Task 4: Find the Word

Ask the user to enter a sentence and a word. Use .find() to print the position of that word.

# Example input: "Python is easy", word: "easy"
# Expected output: Word found at position 10

Task 5: Replace Bad Words

Write a program that replaces words like "bad" or "ugly" with "***" in a sentence.

# Input: "This food is bad and ugly"
# Output: "This food is *** and ***"

Task 6: Count Substring Occurrence

Use .find() inside a loop to count how many times a word appears.

✅ Tasks: split()

Task 7: Split a Sentence into Words

Write a program to split a user-provided sentence into words and print them one per line.

# Input: "Python is fun"
# Output:
# Python
# is
# fun

Task 8: CSV Splitter

Split this string: "Alice,Math,85" and print each part labeled (e.g., Name, Subject, Marks).

# Output:
# Name: Alice
# Subject: Math
# Marks: 85

Task 9: Word Count

Ask the user for a sentence and print the number of words in it using split().

✅ Tasks: partition()

Task 10: Email Parser

Ask the user for an email and extract the username and domain using partition("@").

# Input: "user123@gmail.com"
# Output:
# Username: user123
# Domain: gmail.com

Task 11: Separate Front and Back

Partition a string at a given word and print what's before and after.

# Input: "The quick brown fox", partition word: "brown"
# Output:
# Before: The quick
# After: fox

Task 12: Handle Missing Separator

Use partition() on a string that doesn't contain the separator and show the output tuple.