User-Defined Exception in Python with example

User-Defined Exception in Python

Exception	Description
Exception	Base class for all exceptions.
StopIteration	It generated when the next() method of an iterator does not point to any object.
SystemExit	It raised by sys.exit() function
StandardError	Base class for all built-in exceptions.
ArithmeticError	Base class for errors that are generated due to mathematical calculations.
OverflowError	It raised when the maximum limit of a numeric type is executed during a calculation.
FloatingPointError	It raised when a floating-point calculation could not be performed.
ZeroDivisionError	It raised when a number is divided by zero.
AssertionError	It raised when the assert statement fails.
AttributeError	It raised when attribute reference or assignment fails.
EOFError	It raised when end-of-file is reached
ImportError	It raised when an import statement fails.
KeyboardInterrupt	It raised when the user interrupts program execution.
LookupError	Base class for all lookup errors.
IndexError	It raised when an index is not found in a sequence.
KeyError	It raised when a key is not found in the dictionary.
NameError	It raised when an identifier is not found in the local or global namespace.
UnboundLocalError	It raised when an attempt is made to access a local variable in a function.
EnvironementError	It raised when no value has been assigned to it.
IOError	It raised when input or output operation fails.
SyntaxError	It raised when there is a syntax error in the program
IndentationError	It raised when there is an indentation problem in the program
SystemError	It raised when an internal system error occurs
ValueError	It raised when the arguments passed to a function are of invalid data type.
RuntimeError	It raised when the generated error does not fail into any of the above category.
NotImplementedError	It raised when an abstract method that needs to be implemented in an inherited class is not implemented
TypeError	It raised when two or more data types are mixed without coercion.

Python allows programmers to create their exceptions by creating a new exception class. The new exception class is derived from the base class Exception which is pre-defined in Python.

Example:

class Error(Exception):
def __init__(self, val):
self.val=val
def __str__(self):
return repr(self.val)
try:
raise Error(10)
except Error as e:
print('User-defined Exception value is:', e.val)

Output:
User-defined Exception value is: 10