- How to handle exceptions using the try, except, and finally statements<\/li>
- How to create a custom exception<\/li>
- How to raise an exceptions<\/li>
- How to use built-in exception effectively to build robust Python programs<\/li><\/ul>\n\n\n\n
![\"Python](\"https:\/\/pynative.com\/wp-content\/uploads\/2021\/03\/python_exception_handling.png\")
Python Exceptions<\/figcaption><\/figure><\/div>\n\n\n\n Table of contents<\/h2>
- What are Exceptions?<\/a>
- Why use Exception<\/a><\/li><\/ul><\/li>
- What are Errors?<\/a>
- Syntax error<\/a><\/li>
- Logical errors (Exception)<\/a><\/li><\/ul><\/li>
- Built-in Exceptions<\/a><\/li>
- The try and except Block to Handling Exceptions<\/a>
- Catching Specific Exceptions <\/a><\/li>
- Handle multiple exceptions with a single except clause<\/a><\/li><\/ul><\/li>
- Using try with finally<\/a><\/li>
- Using try with else clause<\/a><\/li>
- Raising an Exceptions<\/a><\/li>
- Exception Chaining<\/a><\/li>
- Custom and User-defined Exceptions<\/a>
- Customizing Exception Classes<\/a><\/li><\/ul><\/li>
- Exception Lifecycle<\/a><\/li>
- Warnings<\/a><\/li><\/ul><\/div>\n\n\n\n
What are Exceptions?<\/h2>\n\n\n\n
An exception is an event that occurs during the execution of programs that disrupt the normal flow of execution<\/strong> (e.g., KeyError Raised when a key is not found in a dictionary.) An exception is a Python object that represents an error..<\/p>\n\n\n\n
In Python, an exception is an object derives from the BaseException<\/strong> class that contains information about an error event that occurred within a method. Exception object contains<\/strong>:<\/p>\n\n\n\n
- Error type (exception name)<\/li>
- The state of the program when the error occurred<\/li>
- An error message describes the error event.<\/li><\/ul>\n\n\n\n
Exception are useful to indicate different types of possible failure condition.<\/p>\n\n\n\n
For example, bellow are the few standard exceptions <\/p>\n\n\n\n
- FileNotFoundException<\/li>
- ImportError<\/li>
- RuntimeError<\/li>
- NameError<\/li>
- TypeError<\/li><\/ul>\n\n\n\n
In Python, we can throw an exception in the try block and catch it in except block.<\/p>\n\n\n\n
Why use Exception<\/h3>\n\n\n\n
- Standardized error handling<\/strong>: Using built-in exceptions or creating a custom exception with a more precise name and description, you can adequately define the error event, which helps you debug the error event.<\/li>
- Cleaner code<\/strong>: Exceptions separate the error-handling code from regular code, which helps us to maintain large code easily.<\/li>
- Robust application<\/strong>: With the help of exceptions, we can develop a solid application, which can handle error event efficiently<\/li>
- Exceptions propagation<\/strong>: By default, the exception propagates the call stack if you don’t catch it. For example, if any error event occurred in a nested function, you do not have to explicitly catch-and-forward it; automatically, it gets forwarded to the calling function where you can handle it.<\/li>
- Different error types<\/strong>: Either you can use built-in exception or create your custom exception and group them by their generalized parent class, or Differentiate errors by their actual class<\/li><\/ul>\n\n\n\n
What are Errors?<\/h2>\n\n\n\n
On the other hand, An error<\/strong> is an action that is incorrect or inaccurate. For example, syntax error. Due to which the program fails to execute.<\/p>\n\n\n\n
The errors can be broadly classified into two types:<\/p>\n\n\n\n
- Syntax errors<\/li>
- Logical errors<\/li><\/ol>\n\n\n\n
Syntax error<\/h4>\n\n\n\n
The syntax error occurs when we are not following the proper structure or syntax of the language. A syntax error is also known as a parsing error<\/strong>.<\/p>\n\n\n\n
When Python parses the program and finds an incorrect statement it is known as a syntax error. When the parser found a syntax error it exits with an error message without running anything.<\/p>\n\n\n\n
Common Python Syntax errors:<\/strong><\/p>\n\n\n\n
- Incorrect indentation<\/li>
- Missing colon, comma, or brackets<\/li>
- Putting keywords in the wrong place.<\/li><\/ul>\n\n\n\n
Example<\/strong><\/p>\n\n\n
- Cleaner code<\/strong>: Exceptions separate the error-handling code from regular code, which helps us to maintain large code easily.<\/li>
- Standardized error handling<\/strong>: Using built-in exceptions or creating a custom exception with a more precise name and description, you can adequately define the error event, which helps you debug the error event.<\/li>
- Exception Lifecycle<\/a><\/li>
- Handle multiple exceptions with a single except clause<\/a><\/li><\/ul><\/li>
- Logical errors (Exception)<\/a><\/li><\/ul><\/li>
- What are Errors?<\/a>
- Why use Exception<\/a><\/li><\/ul><\/li>
- What are Exceptions?<\/a>