Week 3: Git Fundamentals & Python Basics

Week 3: Git Fundamentals & Python Basics

Learning Objectives

By the end of this week, you will be able to:

  • Use essential Git commands for version control
  • Understand Git workflow (add, commit, push, pull)
  • Write basic Python programs with variables and data types
  • Use Python control flow structures (if/else, loops)
  • Define and use simple functions

Part 1: Git Fundamentals

Why Git?

Git is the industry standard for version control. It helps you:

  • Track changes to your code over time
  • Collaborate with others without conflicts
  • Recover from mistakes
  • Maintain multiple versions of your project

Essential Git Commands

1. Setting Up Git

# Configure your identity (one-time setup)
git config --global user.name "Your Name"
git config --global user.email "your.email@example.com"

# Check your configuration
git config --list

2. Creating a Repository

# Initialize a new repository
git init

# Clone an existing repository
git clone https://github.com/username/repository.git

3. Basic Workflow

# Check status of your files
git status

# Add files to staging area
git add filename.py        # Add specific file
git add .                   # Add all files

# Commit changes with message
git commit -m "Add feature X"

# Push to remote repository
git push origin main

# Pull latest changes from remote
git pull origin main

4. Viewing History

# View commit history
git log

# View compact history
git log --oneline

# View differences
git diff                    # Unstaged changes
git diff --staged           # Staged changes

Git Best Practices

  1. Commit Often: Make small, logical commits
  2. Write Clear Messages: Describe what and why, not how
  3. Pull Before Push: Always sync before pushing changes
  4. Use .gitignore: Don’t track unnecessary files

Example .gitignore for Python:

# Python
__pycache__/
*.py[cod]
.env
venv/
*.log

# IDE
.vscode/
.idea/
*.swp

# OS
.DS_Store
Thumbs.db

Part 2: Python Fundamentals

Variables and Data Types

Basic Data Types

# Numbers
integer_num = 42
float_num = 3.14

# Strings
name = "Alice"
message = 'Hello, World!'
multiline = """This is a
multiline string"""

# Booleans
is_student = True
is_finished = False

# None (represents absence of value)
result = None

Type Checking and Conversion

# Check type
print(type(42))          # <class 'int'>
print(type(3.14))        # <class 'float'>
print(type("hello"))     # <class 'str'>

# Type conversion
str_num = "123"
int_num = int(str_num)   # Convert to integer
float_num = float(str_num) # Convert to float
str_val = str(42)        # Convert to string

Basic Operations

# Arithmetic
a = 10 + 5    # Addition: 15
b = 10 - 5    # Subtraction: 5
c = 10 * 5    # Multiplication: 50
d = 10 / 5    # Division: 2.0
e = 10 // 3   # Floor division: 3
f = 10 % 3    # Modulo: 1
g = 2 ** 3    # Exponentiation: 8

# String operations
greeting = "Hello" + " " + "World"  # Concatenation
repeated = "Ha" * 3                 # "HaHaHa"
length = len("Python")               # 6

Control Flow

If/Else Statements

age = 18

if age >= 18:
    print("You are an adult")
elif age >= 13:
    print("You are a teenager")
else:
    print("You are a child")

# Ternary operator
status = "adult" if age >= 18 else "minor"

Loops

# For loop
for i in range(5):
    print(i)  # Prints 0, 1, 2, 3, 4

# Iterating over a list
fruits = ["apple", "banana", "orange"]
for fruit in fruits:
    print(f"I like {fruit}")

# While loop
count = 0
while count < 5:
    print(f"Count: {count}")
    count += 1

# Break and continue
for i in range(10):
    if i == 3:
        continue  # Skip 3
    if i == 7:
        break     # Stop at 7
    print(i)

Functions

Defining Functions

# Simple function
def greet():
    print("Hello!")

greet()  # Call the function

# Function with parameters
def greet_person(name):
    print(f"Hello, {name}!")

greet_person("Alice")

# Function with return value
def add(a, b):
    return a + b

result = add(3, 5)  # result = 8

# Function with default parameters
def power(base, exponent=2):
    return base ** exponent

print(power(3))     # 9 (3^2)
print(power(3, 3))  # 27 (3^3)

Function Documentation

def calculate_area(radius):
    """
    Calculate the area of a circle.

    Args:
        radius (float): The radius of the circle

    Returns:
        float: The area of the circle
    """
    import math
    return math.pi * radius ** 2

# Access documentation
help(calculate_area)

Input and Output

# Getting user input
name = input("Enter your name: ")
age = int(input("Enter your age: "))  # Convert to integer

# Formatted output
print(f"Hello, {name}! You are {age} years old.")

# Writing to a file
with open("output.txt", "w") as f:
    f.write("Hello, World!\n")
    f.write("This is a test.")

# Reading from a file
with open("output.txt", "r") as f:
    content = f.read()
    print(content)

Practice Exercises

Exercise 1: Git Practice

  1. Create a new Git repository
  2. Create a Python file called hello.py
  3. Add and commit the file
  4. Make changes to the file
  5. View the differences
  6. Commit the changes

Exercise 2: Temperature Converter

Write a function that converts Celsius to Fahrenheit:

def celsius_to_fahrenheit(celsius):
    # Your code here
    pass

# Test cases
print(celsius_to_fahrenheit(0))   # Should print 32
print(celsius_to_fahrenheit(100)) # Should print 212

Exercise 3: Number Guesser

Create a simple guessing game:

import random

secret = random.randint(1, 10)
attempts = 0

while True:
    guess = int(input("Guess a number (1-10): "))
    attempts += 1

    if guess == secret:
        print(f"Correct! It took you {attempts} attempts.")
        break
    elif guess < secret:
        print("Too low!")
    else:
        print("Too high!")

Exercise 4: List Operations

# Create a function that finds the maximum in a list
def find_max(numbers):
    if not numbers:
        return None

    max_num = numbers[0]
    for num in numbers:
        if num > max_num:
            max_num = num
    return max_num

# Test
test_list = [3, 7, 2, 9, 1, 5]
print(find_max(test_list))  # Should print 9

Common Pitfalls and Solutions

Git Pitfalls

  1. Forgetting to pull before push
    • Solution: Always run git pull before git push
  2. Committing sensitive data
    • Solution: Use .gitignore and never commit passwords or API keys
  3. Large commits with unrelated changes
    • Solution: Make small, focused commits

Python Pitfalls

  1. Indentation errors
    • Python uses indentation to define blocks
    • Use consistent spacing (4 spaces recommended)
  2. Type errors 
    # Wrong
age = input("Enter age: ")
if age > 18:  # Error: comparing string with int

# Correct
age = int(input("Enter age: "))
if age > 18:
  3. Mutable default arguments 
    # Wrong
def add_item(item, list=[]):
    list.append(item)
    return list

# Correct
def add_item(item, list=None):
    if list is None:
        list = []
    list.append(item)
    return list

Summary

This week you learned:

Git:

  • Initialize and clone repositories
  • Add, commit, and push changes
  • Pull updates from remote repositories
  • View history and differences

Python:

  • Work with basic data types
  • Use control flow structures
  • Define and call functions
  • Handle input and output

These fundamentals form the foundation for all your future programming work. Practice these concepts regularly to build muscle memory and confidence.

Next Week Preview

In Week 4, we’ll dive deeper into:

  • Python data structures (lists, dictionaries, sets)
  • Object-oriented programming basics
  • More advanced Git features (branches, merging)
  • Error handling and debugging

Additional Resources