Now, let's move to the next topic in the Python Coding Challenge:

Strings & String Methods

A string is a sequence of characters inside quotes. You can use:

name = "Alice"
greeting = 'Hello!'
paragraph = """This is
a multiline string."""

👉 Strings are immutable — once created, they can't be changed directly.


✨ Common String Methods

Here are some useful methods you’ll use all the time:

lower() → makes everything lowercase

upper() → makes everything uppercase

strip() → removes spaces from start and end

replace("old", "new") → replaces parts of a string

split() → splits text into a list of words

count("word") → counts how many times something appears

find("word") → finds the position of a word

startswith("Hello") → checks how a string begins

endswith("world") → checks how a string ends


🧪 Examples

msg = " Python is Awesome! "

print(msg.lower()) # python is awesome!
print(msg.strip()) # Python is Awesome!
print(msg.replace("Awesome", "Powerful")) # Python is Powerful!
print(msg.split()) # ['Python', 'is', 'Awesome!']


🛠 Project 1: Word Counter

text = input("Enter a sentence: ")
words = text.split()
print("Word count:", len(words))

Try it with:

> Python is easy and powerful
→ Output: 5


🌀 Project 2: Palindrome Checker

text = input("Enter a word: ")
if text == text[::-1]:
print("Palindrome!")
else:
print("Not a palindrome.")

Try:

- madam → Palindrome
- racecar → Palindrome
- hello → Not a palindrome

React with ❤️ once you’re ready for the quiz

Now, Let's move to the next topic in the Python Coding Challenge:

Lists & Tuples

🔹 What is a List?

A list is a mutable (changeable) collection of items in a specific order.

Syntax:

fruits = ["apple", "banana", "cherry"]

print(fruits[0]) # Output: apple

fruits.append("mango")

print(fruits) # Output: ['apple', 'banana', 'cherry', 'mango']

✅ You can add, remove, or update elements in a list.


🔸 What is a Tuple?

A tuple is similar to a list, but it's immutable (unchangeable once defined).

Syntax:

colors = ("red", "green", "blue")
print(colors[1]) # Output: green

🔒 You cannot modify, append, or remove elements from a tuple after creation.


✅ Key Differences:

Mutability:

- List: Mutable — you can change, add, or remove elements after creation.
- Tuple: Immutable — once defined, you cannot change, add, or remove elements.


Syntax:

- List: Use square brackets → []

my_list = [1, 2, 3]

- Tuple: Use round brackets → ()

my_tuple = (1, 2, 3)


Use Case:

- List: Use when you need to modify the collection later.

- Tuple: Use when the data should remain constant or to ensure integrity.

Performance:

Tuple is slightly faster than List due to immutability and fixed size.


🛠 Mini Project: Grocery List Manager

Let’s build a simple grocery list app where you can:

- Add items

- Remove items

- Display all items

Python Code:

grocery_list = []

while True:
print("\nOptions: add / remove / show / exit")
action = input("What would you like to do? ")

if action == "add":
item = input("Enter item to add: ")
grocery_list.append(item)
print(f"{item} added.")

elif action == "remove":
item = input("Enter item to remove: ")
if item in grocery_list:
grocery_list.remove(item)
print(f"{item} removed.")
else:
print("Item not found.")

elif action == "show":
print("Your grocery list:")
for i in grocery_list:
print("-", i)

elif action == "exit":
break

else:
print("Invalid option.")

✅ Try running this and see how lists work in real time!


React with ❤️ once you’re ready for the quiz

Today, let's move on to the next topic in the Python Coding Challenge:

Dictionaries & Sets 🔑🧺

🔹Day 5: What is a Dictionary in Python?

A dictionary is an unordered, mutable collection that stores data in key-value pairs.

🧠 Example:

student = {
"name": "Amit",
"age": 21,
"course": "Python"
}

print(student["name"]) # Output: Amit

- Keys must be unique and immutable (like strings, numbers).
- Values can be anything: strings, numbers, lists, or even other dictionaries.


🧰 Common Dictionary Methods:

student.get("age") # Returns 21
student.keys() # Returns all keys
student.values() # Returns all values
student.items() # Returns key-value pairs
student["grade"] = "A+" # Adds a new key-value pair


🔹 What is a Set in Python?

A set is an unordered collection of unique elements.

🧠 Example :

numbers = {1, 2, 3, 4, 4, 2}
print(numbers) # Output: {1, 2, 3, 4} — no duplicates

- Sets remove duplicates automatically.
- Useful for membership checks, uniqueness, and set operations (union, intersection).


✅ Real-Life Project: Contact Book using Dictionary

- Build a CLI-based contact book where users can:
- Add new contacts (name, phone)
- View all contacts
- Search by name
- Delete a contact


💡 Python Code:

contacts = {}

while True:
print("\n1. Add Contact\n2. View All\n3. Search\n4. Delete\n5. Exit")
choice = input("Enter choice: ")

if choice == '1':
name = input("Name: ")
phone = input("Phone: ")
contacts[name] = phone
print("Contact saved!")

elif choice == '2':
for name, phone in contacts.items():
print(f"{name} : {phone}")

elif choice == '3':
name = input("Enter name to search: ")
if name in contacts:
print(f"{name}'s phone: {contacts[name]}")
else:
print("Contact not found.")

elif choice == '4':
name = input("Enter name to delete: ")
if name in contacts:
del contacts[name]
print("Deleted successfully.")
else:
print("No such contact.")

elif choice == '5':
break
else:
print("Invalid choice.")


React with ❤️ once you’re ready for the quiz