Raising Exception

The raise statement allows the programmer to force a specific exception to occur. The sole argument in raise indicates the exception to be raised. This must be either an exception instance or an exception class (a class that derives from Exception).

This code intentionally raises a NameError with the message “Hi there” using the raise statement within a try block. Then, it catches the NameError exception, prints “An exception,” and re-raises the same exception using raise. This demonstrates how exceptions can be raised and handled in Python, allowing for custom error messages and further exception propagation.

The output of the above code will simply line printed as “An exception” but a Runtime error will also occur in the last due to the raise statement in the last line. So, the output on your command line will look like 

Traceback (most recent call last):
  File "/home/d6ec14ca595b97bff8d8034bbf212a9f.py", line 5, in <module>
    raise NameError("Hi there")  # Raise Error
NameError: Hi there

Advantages of Exception Handling:

• Improved program reliability: By handling exceptions properly, you can prevent your program from crashing or producing incorrect results due to unexpected errors or input.
• Simplified error handling: Exception handling allows you to separate error handling code from the main program logic, making it easier to read and maintain your code.
• Cleaner code: With exception handling, you can avoid using complex conditional statements to check for errors, leading to cleaner and more readable code.
• Easier debugging: When an exception is raised, the Python interpreter prints a traceback that shows the exact location where the exception occurred, making it easier to debug your code.

Disadvantages of Exception Handling:

• Performance overhead: Exception handling can be slower than using conditional statements to check for errors, as the interpreter has to perform additional work to catch and handle the exception.
• Increased code complexity: Exception handling can make your code more complex, especially if you have to handle multiple types of exceptions or implement complex error handling logic.
• Possible security risks: Improperly handled exceptions can potentially reveal sensitive information or create security vulnerabilities in your code, so it’s important to handle exceptions carefully and avoid exposing too much information about your program.

Overall, the benefits of exception handling in Python outweigh the drawbacks, but it’s important to use it judiciously and carefully in order to maintain code quality and program reliability.

This article is contributed by Nikhil Kumar Singh(nickzuck_007) 

We have explored basic python till now from Set 1 to 4 (Set 1 | Set 2 | Set 3 | Set 4). 

In this article, we will discuss how to handle exceptions in Python using try, except, and finally statements with the help of proper examples. 

Error in Python can be of two types i.e. Syntax errors and Exceptions. Errors are problems in a program due to which the program will stop the execution. On the other hand, exceptions are raised when some internal events occur which change the normal flow of the program. 

Different types of exceptions in python:

In Python, there are several built-in Python exceptions that can be raised when an error occurs during the execution of a program. Here are some of the most common types of exceptions in Python:

• SyntaxError: This exception is raised when the interpreter encounters a syntax error in the code, such as a misspelled keyword, a missing colon, or an unbalanced parenthesis.
• TypeError: This exception is raised when an operation or function is applied to an object of the wrong type, such as adding a string to an integer.
• NameError: This exception is raised when a variable or function name is not found in the current scope.
• IndexError: This exception is raised when an index is out of range for a list, tuple, or other sequence types.
• KeyError: This exception is raised when a key is not found in a dictionary.
• ValueError: This exception is raised when a function or method is called with an invalid argument or input, such as trying to convert a string to an integer when the string does not represent a valid integer.
• AttributeError: This exception is raised when an attribute or method is not found on an object, such as trying to access a non-existent attribute of a class instance.
• IOError: This exception is raised when an I/O operation, such as reading or writing a file, fails due to an input/output error.
• ZeroDivisionError: This exception is raised when an attempt is made to divide a number by zero.
• ImportError: This exception is raised when an import statement fails to find or load a module.

These are just a few examples of the many types of exceptions that can occur in Python. It’s important to handle exceptions properly in your code using try-except blocks or other error-handling techniques, in order to gracefully handle errors and prevent the program from crashing.