Now, let’s move on to next topic in the Python coding challenge.

Operators in Python

Operators are special symbols or keywords that perform operations on variables and values.

Types of Operators in Python:

1. Arithmetic Operators

Used for basic math:
+ (add), - (subtract), * (multiply), / (divide), // (floor divide), % (modulus), ** (power)

a = 10
b = 3
print(a + b) # 13
print(a ** b) # 1000


2. Comparison Operators

Used to compare two values:
==, !=, >, <, >=, <=

x = 5
print(x == 5) # True
print(x != 3) # True


3. Logical Operators
Used to combine conditional statements:
and, or, not

age = 20
print(age > 18 and age < 25) # True


4. Assignment Operators

Used to assign values to variables:
=, +=, -=, *=, /=, etc.

score = 10
score += 5 # score is now 15


Mini Project: Build a Simple Calculator

Let’s apply what we’ve learned!

Task: Build a calculator that asks the user to enter two numbers and an operator, then prints the result.

Approach

1. Take two numbers from the user.
2. Ask for an operator (+, -, *, /).
3. Perform the operation based on what the user entered.
4. Print the result, or shows "Invalid operator!" if the input is wrong.

Python Code:

num1 = float(input("Enter first number: "))
op = input("Enter operator (+, -, *, /): ")
num2 = float(input("Enter second number: "))

if op == "+":
print(num1 + num2)
elif op == "-":
print(num1 - num2)
elif op == "*":
print(num1 * num2)
elif op == "/":
print(num1 / num2)
else:
print("Invalid operator!")

React with ❤️ once you’re ready for the quiz

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