Create beginner-friendly Python learning repository with structured examples and practice problems

01_Variables_and_Data_Types/01_basic_variables.py

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+"""
+Basic Variables in Python
+==========================
+This program demonstrates how to create and use variables in Python.
+Variables are containers for storing data values.
+"""
+
+# Creating variables with different data types
+name = "Alice"              # String variable
+age = 20                    # Integer variable
+height = 5.6               # Float variable
+is_student = True          # Boolean variable
+
+# Printing variables
+print("=== Student Information ===")
+print("Name:", name)
+print("Age:", age)
+print("Height:", height, "feet")
+print("Is Student:", is_student)
+
+# You can change variable values
+print("\n=== After one year ===")
+age = age + 1              # Increasing age by 1
+print("Age:", age)
+
+# Multiple variables in one line
+x, y, z = 10, 20, 30
+print("\n=== Multiple Variables ===")
+print("x =", x)
+print("y =", y)
+print("z =", z)
+
+# Same value to multiple variables
+a = b = c = 100
+print("\n=== Same Value to Multiple Variables ===")
+print("a =", a)
+print("b =", b)
+print("c =", c)
+
+# Variable naming rules demonstration
+student_name = "Bob"       # Good: descriptive and uses snake_case
+_private_var = 42          # Good: starts with underscore (convention for private)
+# 2nd_student = "Charlie"  # Bad: cannot start with number (commented out)
+
+print("\n=== Variable Naming ===")
+print("Student Name:", student_name)
+print("Private Variable:", _private_var)

01_Variables_and_Data_Types/02_numbers.py

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+"""
+Working with Numbers in Python
+===============================
+This program demonstrates integer and float operations.
+"""
+
+# Integer examples
+num1 = 10
+num2 = 3
+
+print("=== Integer Operations ===")
+print("Number 1:", num1)
+print("Number 2:", num2)
+print("Addition:", num1 + num2)
+print("Subtraction:", num1 - num2)
+print("Multiplication:", num1 * num2)
+print("Division:", num1 / num2)           # Returns float
+print("Floor Division:", num1 // num2)    # Returns integer (rounds down)
+print("Modulus (Remainder):", num1 % num2)
+print("Power:", num1 ** num2)             # 10 to the power of 3
+
+# Float examples
+price1 = 19.99
+price2 = 5.50
+
+print("\n=== Float Operations ===")
+print("Price 1: $", price1)
+print("Price 2: $", price2)
+print("Total Price: $", price1 + price2)
+print("Average Price: $", (price1 + price2) / 2)
+
+# Mixed operations (int and float)
+quantity = 5                    # Integer
+price_per_item = 12.50         # Float
+total = quantity * price_per_item
+
+print("\n=== Shopping Bill ===")
+print("Quantity:", quantity)
+print("Price per item: $", price_per_item)
+print("Total amount: $", total)
+
+# Useful number functions
+number = -42.7
+
+print("\n=== Number Functions ===")
+print("Original number:", number)
+print("Absolute value:", abs(number))      # Removes negative sign
+print("Rounded value:", round(number))     # Rounds to nearest integer
+print("Rounded to 1 decimal:", round(number, 1))
+
+# Finding max and min
+a, b, c = 15, 28, 9
+print("\n=== Max and Min ===")
+print("Numbers:", a, b, c)
+print("Maximum:", max(a, b, c))
+print("Minimum:", min(a, b, c))

01_Variables_and_Data_Types/03_strings.py

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+"""
+Working with Strings in Python
+===============================
+This program demonstrates string operations and methods.
+"""
+
+# Creating strings
+name = "Alice"
+message = 'Hello World'
+multiline = """This is a
+multi-line
+string"""
+
+print("=== Basic Strings ===")
+print("Name:", name)
+print("Message:", message)
+print("Multiline String:")
+print(multiline)
+
+# String concatenation (joining)
+first_name = "John"
+last_name = "Doe"
+full_name = first_name + " " + last_name
+
+print("\n=== String Concatenation ===")
+print("First Name:", first_name)
+print("Last Name:", last_name)
+print("Full Name:", full_name)
+
+# String repetition
+laugh = "ha"
+print("\n=== String Repetition ===")
+print("Laugh:", laugh * 5)  # Prints "hahahahaha"
+
+# String length
+sentence = "Python is fun"
+print("\n=== String Length ===")
+print("Sentence:", sentence)
+print("Length:", len(sentence))
+
+# Accessing characters (indexing)
+word = "Python"
+print("\n=== String Indexing ===")
+print("Word:", word)
+print("First character:", word[0])    # P
+print("Second character:", word[1])   # y
+print("Last character:", word[-1])    # n
+print("Second last:", word[-2])       # o
+
+# String slicing
+text = "Hello World"
+print("\n=== String Slicing ===")
+print("Original text:", text)
+print("First 5 characters:", text[0:5])    # Hello
+print("From index 6 to end:", text[6:])    # World
+print("Last 5 characters:", text[-5:])     # World
+
+# Useful string methods
+sample = "  python programming  "
+print("\n=== String Methods ===")
+print("Original:", "[" + sample + "]")
+print("Uppercase:", sample.upper())
+print("Lowercase:", sample.lower())
+print("Capitalized:", sample.capitalize())
+print("Stripped (remove spaces):", "[" + sample.strip() + "]")
+print("Replace:", sample.replace("python", "Python"))
+
+# Checking string content
+email = "student@example.com"
+print("\n=== String Checks ===")
+print("Email:", email)
+print("Contains '@':", "@" in email)
+print("Starts with 'student':", email.startswith("student"))
+print("Ends with '.com':", email.endswith(".com"))
+
+# String formatting
+name = "Alice"
+age = 20
+print("\n=== String Formatting ===")
+# Method 1: f-strings (recommended)
+print(f"My name is {name} and I am {age} years old.")
+# Method 2: format() method
+print("My name is {} and I am {} years old.".format(name, age))
+# Method 3: % operator (old style)
+print("My name is %s and I am %d years old." % (name, age))

01_Variables_and_Data_Types/04_lists.py

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+"""
+Working with Lists in Python
+=============================
+This program demonstrates list operations and methods.
+Lists are ordered, mutable collections that can contain different data types.
+"""
+
+# Creating lists
+fruits = ["apple", "banana", "orange"]
+numbers = [1, 2, 3, 4, 5]
+mixed = [1, "hello", 3.14, True]
+empty_list = []
+
+print("=== Creating Lists ===")
+print("Fruits:", fruits)
+print("Numbers:", numbers)
+print("Mixed types:", mixed)
+print("Empty list:", empty_list)
+
+# Accessing list elements
+print("\n=== Accessing Elements ===")
+print("First fruit:", fruits[0])
+print("Second fruit:", fruits[1])
+print("Last fruit:", fruits[-1])
+
+# List length
+print("\n=== List Length ===")
+print("Number of fruits:", len(fruits))
+
+# Adding elements to list
+fruits.append("grape")              # Add at the end
+print("\n=== Adding Elements ===")
+print("After append:", fruits)
+
+fruits.insert(1, "mango")           # Insert at specific position
+print("After insert at position 1:", fruits)
+
+# Removing elements from list
+fruits.remove("banana")             # Remove specific item
+print("\n=== Removing Elements ===")
+print("After removing banana:", fruits)
+
+last_fruit = fruits.pop()           # Remove and return last item
+print("Popped item:", last_fruit)
+print("After pop:", fruits)
+
+# List slicing
+numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+print("\n=== List Slicing ===")
+print("Original list:", numbers)
+print("First 5 elements:", numbers[0:5])
+print("Elements from index 5:", numbers[5:])
+print("Last 3 elements:", numbers[-3:])
+print("Every second element:", numbers[::2])
+
+# List operations
+list1 = [1, 2, 3]
+list2 = [4, 5, 6]
+print("\n=== List Operations ===")
+print("List 1:", list1)
+print("List 2:", list2)
+print("Concatenation:", list1 + list2)
+print("Repetition:", list1 * 3)
+
+# Useful list methods
+numbers = [3, 1, 4, 1, 5, 9, 2, 6]
+print("\n=== List Methods ===")
+print("Original list:", numbers)
+print("Count of 1:", numbers.count(1))
+print("Index of 4:", numbers.index(4))
+
+numbers.sort()                      # Sort in ascending order
+print("Sorted list:", numbers)
+
+numbers.reverse()                   # Reverse the list
+print("Reversed list:", numbers)
+
+# Checking if item exists in list
+shopping_list = ["milk", "bread", "eggs", "butter"]
+print("\n=== Checking Items ===")
+print("Shopping list:", shopping_list)
+print("Is 'milk' in list?", "milk" in shopping_list)
+print("Is 'cheese' in list?", "cheese" in shopping_list)
+
+# List comprehension (advanced but useful)
+squares = [x**2 for x in range(1, 6)]
+print("\n=== List Comprehension ===")
+print("Squares of 1-5:", squares)

01_Variables_and_Data_Types/05_tuples.py

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+"""
+Working with Tuples in Python
+==============================
+This program demonstrates tuple operations.
+Tuples are ordered, immutable collections (cannot be changed after creation).
+"""
+
+# Creating tuples
+coordinates = (10, 20)
+rgb_color = (255, 0, 0)
+mixed_tuple = (1, "hello", 3.14, True)
+single_item = (42,)                 # Note: comma is required for single item
+empty_tuple = ()
+
+print("=== Creating Tuples ===")
+print("Coordinates:", coordinates)
+print("RGB Color:", rgb_color)
+print("Mixed tuple:", mixed_tuple)
+print("Single item tuple:", single_item)
+print("Empty tuple:", empty_tuple)
+
+# Accessing tuple elements
+point = (100, 200, 300)
+print("\n=== Accessing Elements ===")
+print("Point:", point)
+print("X coordinate:", point[0])
+print("Y coordinate:", point[1])
+print("Z coordinate:", point[2])
+print("Last element:", point[-1])
+
+# Tuple length
+print("\n=== Tuple Length ===")
+print("Length of point:", len(point))
+
+# Tuple unpacking
+x, y, z = point
+print("\n=== Tuple Unpacking ===")
+print("x =", x)
+print("y =", y)
+print("z =", z)
+
+# Why use tuples? They are immutable
+print("\n=== Immutability Demo ===")
+print("Original coordinates:", coordinates)
+# coordinates[0] = 30  # This would cause an error!
+print("Tuples cannot be changed after creation")
+
+# Tuple methods (only 2 methods since tuples are immutable)
+numbers = (1, 2, 3, 2, 4, 2, 5)
+print("\n=== Tuple Methods ===")
+print("Numbers:", numbers)
+print("Count of 2:", numbers.count(2))
+print("Index of 4:", numbers.index(4))
+
+# Tuple operations
+tuple1 = (1, 2, 3)
+tuple2 = (4, 5, 6)
+print("\n=== Tuple Operations ===")
+print("Tuple 1:", tuple1)
+print("Tuple 2:", tuple2)
+print("Concatenation:", tuple1 + tuple2)
+print("Repetition:", tuple1 * 3)
+
+# Converting between lists and tuples
+my_list = [1, 2, 3, 4, 5]
+my_tuple = tuple(my_list)
+back_to_list = list(my_tuple)
+
+print("\n=== List and Tuple Conversion ===")
+print("Original list:", my_list)
+print("Converted to tuple:", my_tuple)
+print("Back to list:", back_to_list)
+
+# Practical use case: returning multiple values from a function
+def get_student_info():
+    """Returns student information as a tuple"""
+    name = "Alice"
+    age = 20
+    grade = "A"
+    return (name, age, grade)  # Or just: return name, age, grade
+
+print("\n=== Practical Use Case ===")
+student_data = get_student_info()
+print("Student data (tuple):", student_data)
+
+# Unpacking the returned tuple
+student_name, student_age, student_grade = get_student_info()
+print(f"Name: {student_name}, Age: {student_age}, Grade: {student_grade}")
+
+# When to use tuples vs lists?
+print("\n=== When to Use Tuples ===")
+print("Use tuples when:")
+print("  1. Data should not change (coordinates, RGB values)")
+print("  2. Returning multiple values from a function")
+print("  3. Using as dictionary keys (lists can't be keys)")
+print("  4. Slightly faster than lists")