Custom exceptions allow you to create your own error types.
They are useful when built-in exceptions do not clearly describe your program\u2019s specific error.<\/p>\n\n\n\n
Custom exceptions make your code more readable, professional, and organized.<\/p>\n\n\n\n
\u2022 Enforce business rules
\u2022 Improve error clarity
\u2022 Make debugging easier
\u2022 Handle application-specific problems<\/p>\n\n\n\n
To create a custom exception, define a class that inherits from Now you can use this exception in your program.<\/p>\n\n\n\n If the user enters a negative age, the custom exception will be raised.<\/p>\n\n\n\n Here, the custom exception is raised and handled properly.<\/p>\n\n\n\n You can customize the exception class further.<\/p>\n\n\n\n Example: Bank account balance validation<\/p>\n\n\n\n This makes your application logic clearer and more structured.<\/p>\n\n\n\n \u2022 Inherit from Custom exceptions allow you to define and handle application-specific errors clearly and professionally, making your Python programs stronger and easier to maintain.<\/p>\n\n\n\n <\/p> <\/div> <\/div>\n\n\nException<\/code>.<\/p>\n\n\n\nclass CustomError(Exception):
pass<\/pre>\n\n\n\nSIMPLE EXAMPLE<\/strong><\/h2>\n\n\n\n
class InvalidAgeError(Exception):
passage = int(input(\"Enter your age: \"))if age < 0:
raise InvalidAgeError(\"Age cannot be negative.\")print(\"Age accepted.\")<\/pre>\n\n\n\nUSING CUSTOM EXCEPTION WITH TRY-EXCEPT<\/strong><\/h2>\n\n\n\n
class InvalidMarksError(Exception):
passtry:
marks = int(input(\"Enter marks: \"))
if marks < 0 or marks > 100:
raise InvalidMarksError(\"Marks must be between 0 and 100.\")
except InvalidMarksError as e:
print(\"Error:\", e)<\/pre>\n\n\n\nADDING CUSTOM MESSAGE WITH INIT<\/strong><\/h2>\n\n\n\n
class NegativeNumberError(Exception):
def __init__(self, message):
self.message = message
super().__init__(self.message)try:
num = int(input(\"Enter number: \"))
if num < 0:
raise NegativeNumberError(\"Negative numbers are not allowed.\")
except NegativeNumberError as e:
print(\"Error:\", e)<\/pre>\n\n\n\nREAL-WORLD USE CASE<\/strong><\/h2>\n\n\n\n
class InsufficientBalanceError(Exception):
passbalance = 500
withdraw = 1000if withdraw > balance:
raise InsufficientBalanceError(\"Not enough balance.\")<\/pre>\n\n\n\nBEST PRACTICES<\/strong><\/h2>\n\n\n\n
Exception<\/code>
\u2022 Use meaningful class names
\u2022 Provide clear error messages
\u2022 Use custom exceptions for specific business logic<\/p>\n\n\n\nKEY TAKEAWAY<\/strong><\/h2>\n\n\n\n