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
2August 3, 2025 676 1
