Unit 6 - Lesson 6

62.1.1. Raising an exception

def checkage(age):
    if age < 0:
        raise ValueError("age should be greater than or equal to zero")
    print("age is valid")
# write your code here
try:
    a = int(input("age: "))
    checkage(a)
except ValueError as e:
    print(f"('{e}',)")
finally:
    print("executed in any condition")

62.1.2. Writing a program of raising an exception

try:
    # write your code here
    def checkage(a):
        if a < 0:
            raise ValueError("age should be greater than or equal to zero")
    a = int(input("age: "))
    checkage(a)
except ValueError:
    print("age should be greater than or equal to zero")
finally:
    print("i am always executed")

62.2.1. User Defined Exceptions - An overview

(a) Python supports a lot of in-built exceptions.
(b) All user defined exceptions have to be derived from the Exception class.
(c) Python built-in exceptions extend from the BaseException/Exception class.

62.2.2. An user defined exception example

class OurException(Exception):
    # define constructor
    def __init__(self,message):
        self.message = message

class UsingUserException:
    try:
        a = int(input("a: "))
        b = int(input("b: "))
        #write code in try block
        if b == 0:
            raise OurException("b should be greater than 0")
        d = a/b
        print("division operation successful with result:",d)

    except OurException as err:
        print("user defined exception:", err.message)

62.2.3. Writing a user defined exception

try:
    a = int(input("a: "))
    b = int(input("b: "))
    def d(a,b):
        if b==0:
            raise ArithmeticError("b should be greater than 0")
        return(a/b)
    print("division operation successful with result:", d(a,b))
except ArithmeticError as e:
    print("user defined exception:",e)

Unit 6 - Lesson 6 | Codetantra Python

Unit 6 - Lesson 6