How to Exit a Try/Except Block in Python

In Python, we often encounter scenarios where specific operations may experience errors or exceptions which can interrupt the flow of the execution or even abruptly terminate the process.

Python’s built-in try/except block is designed to handle such unexpected circumstances in a more controlled way. With it, we can encapsulate our code in such a way that we can not only catch errors but also handle them appropriately.

Understanding Try/Except Block

The try/except block in Python is a compound statement for exception handling. The operations that can possibly throw exceptions are enclosed in the try clause. In case any exception does occur, it gets intercepted in the except clause, where you can specify how to handle these exceptions.

Exiting a Try/Except Block

There are different methods to exit a try/except block based on the situation at hand.

If no exceptions were encountered during the execution of the try clause, Python simply skips the except clause and exits the try/except block once the try clause has finished executing.

However, in cases where an exception does occur, execution transfers from the try clause to the appropriate except clause:

Using the “raise”

To exit from a try block directly upon encountering an exception, the raise keyword is used. The raise statement can be used to trigger an exception explicitly. Here is an example:

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try:
    raise Exception("Triggering an exception")
except Exception as error:
    print(f"Caught an exception: {error}")

Using the “break”

You can also use the break statement to exit from an encapsulating loop where the try/except block is located. An example of this can be demonstrated as follows:

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while True:
    try:
        break
        print("You won't see this message.")
    except Exception as error:
        print(f"Caught an exception: {error}")

A final scenario to mention is using the sys.exit() function provided by the sys module in Python to terminate the program execution.

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import sys
 
try:
    sys.exit()
except Exception as error:
    print(f"Caught an exception: {error}")

Using finally Clause

You can further use a finally clause that will be always executed, whether an exception was raised or not which adds a level of certainty.

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try:
    raise Exception("Triggering an exception")
except Exception as error:
    print(f"Caught an exception: {error}")
finally:
    print("Exiting try/except block.")

Output:

Caught an exception: Triggering an exception
Exiting try/except block.

Full Code

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import sys
 
# using raise
try:
    raise Exception("Triggering an exception")
except Exception as error:
    print(f"Caught an exception: {error}")
 
# using break
while True:
    try:
        break
        print("You won't see this message.")
    except Exception as error:
        print(f"Caught an exception: {error}")
 
# using sys.exit()
try:
    sys.exit()
except Exception as error:
    print(f"Caught an exception: {error}")
 
# using finally clause
try:
    raise Exception("Triggering an exception")
except Exception as error:
    print(f"Caught an exception: {error}")
finally:
    print("Exiting try/except block.")

Conclusion

Exiting a try/except block in Python is quite straightforward and flexible. Depending on your specific requirements, you can utilize the raise, break, or sys.exit() methods. In all cases, using appropriate exception handling in Python results in code that is more robust, reliable, and resilient to runtime errors or exceptions.