What is Exception Handling in Python?

Errors are flaws in a program that causes the program to terminate its execution. Exceptions are raised when internal events occur that disrupt the program’s usual flow. Python has two sorts of errors in syntax and errors in logic(can be handled using exceptions).

A Python object that describes an error is termed an exception. Python has a built-in system for managing exceptions, allowing the program to continue running without interruption. If we do not handle the exception, the interpreter does not run all of the code that follows it.

Runtime errors are an exception that can be managed by the programmer.

As we know In Python, every exception is represented by a class.

A few examples of exceptions(errors) are shown below :

Syntax Error vs. Exceptions: So what is the Difference?

Syntax Error

In any programming language, syntax mistakes are equivalent to grammar or spelling mistakes. Python will not be able to start executing your code if there is such an error. You’ll receive a detailed error notice that explains what’s wrong and how to repair it. As a result, it’s the most straightforward error to resolve.

This error is generated by incorrect syntax in the code, as the name implies. It leads to the program’s discontinuation.

In Python, frequent syntax errors include missing symbols (such as commas, brackets, and colons), misspelling keywords, and inappropriate indentation.

Example:

Output:

Exception

When a program’s syntax is valid but the code produces an error, an exception is thrown. This mistake does not prevent the application from running, but it does disrupt its normal flow.

Example:

Output:

When you try to use a variable or function name that isn’t valid, you’ll get a name error like the one above.

Using try and except to handle an exception in Python

If you have any strange code that could cause an exception, you can prevent your program by inserting it in a try: block. Include an except: statement after the try: block, followed by a block of code that handles the situation as neatly as feasible.

Syntax:

try:

  #Operation

except ExceptionName:

  #handle exception

else:

#run when no exception is raised

finally:

#run anyway

A few key points concerning python exception handling:

• For a single try block, we can write many except blocks.
• To handle several exceptions, we can write multiple except blocks.
• Without a try block, we can’t write an except block.
• Regardless of whether or not an exception occurs,  finally block will be executed.
• The block will be run if no exception is raised. The else block is run after the try block.

Try: The try block contains code that could throw an exception. In try and except blocks, the try keyword is used. It defines a code block that is checked for errors.

Syntax:

try:

  #statements

Example: 

Exception: The try block throws an exception, which is caught in the exception block. There can be more than one except for the try block.

• With the ExceptionClassName:

    Syntax:

     except ExceptionClassName:

#statements

     Example :

Output:

• Exception as object:

 Syntax:

         except ExceptionClassName as e:

#statements

            Example:

          Output: 

• Multiple Exception with a tuple:

Syntax:

except( ExceptionClassName1, ExceptionClassName2…..n):

#statements

Example:

The except clause in Python allows us to define multiple exceptions. When a try block throws many exceptions, declaring multiple exceptions is useful. 

Output:

• Catch many types of Exception:

Syntax :

except:

        #statements

Example:

Output:

This type of try-except statement captures all possible exceptions. However, using this type of try-except statement is not a good programming practice because it catches all exceptions but does not require the programmer to find the root cause of any potential problems.

Else: When no exception is raised, the block will be executed. After the try block, the else block is executed.

Syntax:

else:

#statements 

Example:

Output:

Finally

The finally statement, which can be used with the try statement, is an optional Python statement. It is used to yield the external resource regardless of whether or not an exception occurs. Finally, a guarantee of execution is provided by the finally block.

Irrespective of whether or not there is an exception, this block will be executed.

Syntax:

finally:

#statements

Example:

Output:

Why is it necessary to handle exceptions?

• Python has a built-in system for managing exceptions, allowing the code to continue running without interruption. If we do not manage the exception, the interpreter does not execute all of the code that exists after it.
• When an exception occurs, the program will suddenly end.
• Data loss from a database or file may occur as a result of an exception.

Conclusion

Exceptions are a common feature of programming languages. Exception handlers’ main benefit is that they help in the resolution of issues that arise when resource allocations need to be reversed professionally.

This is another way of explaining that exception handlers assist in preventing resource loss. 

Hope you have understood exception handling in Python. 

However, if you have anymore doubts in Python or stuck with your python project, reach out to us. Our Python developers will help you in completing your project.