Review: Reading Code

It is important to be able to read other people's source code. You may need to tweak examples you find online, read tutorials, or look for bugs that can be exploited. This chapter reviews core Python concepts.

Learning Objectives

You should be able to:

• Explain what the code is doing, line by line

Video Walkthrough

Use this video to follow along with the steps in this lab.

Reading Source Code

Explain what each line of code in the following Python program does.

• Identify the data types.
• Describe function parameters and return values.
• Explain the flow of the program.
• There may be specific libraries or functions you do not recognize. Search for them on the internet if needed.

import requests

settings = {
    "success_message": "Success!",
    "failure_message": "Failure!"
}

def check_connectivity(sites):
    for site in sites:
        print(f"Checking connectivity for {site}...")
        response = requests.get(site)
        if response:
            print(settings['success_message'])
        else:
            print(settings['failure_message'])

if __name__ == "__main__":
    print("Welcome!")
    answer = ""
    while answer != "x":
        print("What would you like to do?")
        print("  1 - check connectivity")
        print("  x - exit")
        answer = input("? ")
        if answer == "1":
            sites = ["https://google.com", "https://microsoft.com", "https://apple.com/doesnotexist"]
            check_connectivity(sites)
        elif answer == "x":
            break
        else:
            print("Unknown option")

Reflection

• Why is it important to be able to read code?
• What weaknesses exist in the program to check connectivity?