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Module 14: Error Handling

Even when we write code carefully, unexpected situations can cause a program to crash during execution. For example:

  • An internet connection drops.
  • A file we want to open does not exist on the system.
  • A user enters text when a number is expected.

In such situations, we want to prevent the program from stopping abruptly (crashing) and instead handle the issue gracefully so the execution can continue. This process is called Error Handling.

Real-world Analogy​

Think of a trapeze artist performing in a circus. Even though they practice extensively, there is always a risk of falling. To prevent injury, a safety net is installed below them. If they fall, the safety net catches them safely.

In Python, Error Handling acts as a safety net for your code.

Importance in Data Science and AI​

In Data Science and AI workflows, we frequently automate tasks like processing thousands of files or scraping data from websites.

  • If the 500th file out of 1000 files is corrupted, we do not want the entire program to stop.
  • Instead, we want to log the error, skip that file, and continue processing the remaining files.
  • Error handling is crucial for building robust applications that can handle real-world data issues.

What we will learn in this module:​

In this module, we will learn:

  1. What are Errors?: Understanding the basics of errors and their types.
  2. Syntax Errors: Grammatical mistakes in the code that prevent execution.
  3. Runtime Errors (Exceptions): Errors that occur during code execution (e.g., ZeroDivisionError, FileNotFoundError).
  4. Using try and except: How to catch and handle exceptions to prevent crashes.
  5. The finally Block: Code block that runs regardless of whether an error occurred.
  6. The else Block: Code that runs only when no exception occurs.
  7. Raising Exceptions: Using the raise keyword to trigger custom errors.
  8. Custom Exceptions: Creating your own error types for specific situations.

Quick Summary​

  • Error Resilience: Real-world software must anticipate and handle unexpected user inputs and environment failures gracefully.
  • Error Categories: Distinguish between grammar parsing mistakes (Syntax Errors) and execution anomalies (Runtime Exceptions).
  • The Error Handling Toolset: Python uses try, except, else, finally, and raise to build crash-proof applications.

What's Next?​

Let's start by understanding what errors actually are and how Python categorizes them in the next lesson!

What Are Errors in Python?

Understand the difference between syntax errors and runtime exceptions

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