Question

What are the two common variations of the try statement?

Short answer

The two common variations of the try statement are try-except and try-finally.

Step-by-step solution

Identify the Try Statement

The try statement in programming is used to handle exceptions, ensuring that a block of code can be executed and that specific problems can be managed without causing the entire program to crash.

First Variation: Try-Except

The most common variation is the try-except statement. This consists of a try block, which contains the code that might throw an exception, followed by one or more except blocks, which handle specific exceptions that might be thrown.

Second Variation: Try-Finally

The second common variation is the try-finally statement. This consists of a try block, followed by a finally block. The finally block will be executed regardless of whether an exception is thrown or not, ensuring that cleanup actions or other important steps are taken.

Key concepts

exception handling

When writing a program, you might encounter unexpected issues, called exceptions, that can cause your code to stop running. Exception handling is a method to manage these situations gracefully. By using exception handling, your program can react to unforeseen events without crashing. This not only makes your program more robust but also improves the user experience by providing more informative error messages.
In Python, exceptions include errors like:

• ZeroDivisionError: Trying to divide by zero
• FileNotFoundError: File not found during operations like reading or writing
• ValueError: Invalid value

Handling exceptions helps maintain the flow of the program, making it resilient against unexpected input or other runtime anomalies.

try-except block

The try-except block is one of the most common ways to handle exceptions in Python. It allows you to test a block of code (try block) and catch exceptions (except block) if any errors occur. This way, your program can respond to exceptions without stopping abruptly.
Here's the basic structure of a try-except block:

```python
try:
# code that may raise an exception
except SomeException:
# code that runs if the exception occurs
```
You can also specify multiple exceptions:
```python
try:
# code that may raise an exception
except (SomeException, AnotherException):
# code that runs if either exception occurs
```
This block ensures that specific problems are managed, and the program can continue running. For example, attempting to open a file that doesn't exist might raise a `FileNotFoundError` which can be caught and handled appropriately.

try-finally block

The try-finally block is another variation used in Python for exception handling. Unlike the try-except block, the try-finally block ensures that certain code runs no matter what, even if an exception occurs. This is crucial for cleanup actions such as closing a file or releasing resources.
In a try-finally block, you place the code that might throw an exception inside the try block. The finally block contains the code that you want to execute regardless of what happens in the try block.
Here's how it looks in code:
```python
try:
# code that may raise an exception
finally:
# code that will always be executed, whether an exception is raised or not
```
You can also combine try-except and try-finally:
```python
try:
# code that may raise an exception
except SomeException:
# code that runs if the exception occurs
finally:
# code that will always be executed
```
This structure guarantees that important parts of your code are executed regardless of errors, making your program more reliable and robust.