Exception Handling part 1

#example program on without Exception Handling

print("Good afternoon")#

print(4/2)#

print(10/0)#exception raised

print("Thank you")

output:

Good afternoon

2.0

Runtime error : Abnormal termination

with using try..except

#example program on Exception Handling

print("Good afternoon")#

print(4/2)#

try:

    print(10/0)#exception raised

except ZeroDivisionError:

    print("division by zero is not possible")

print("Thank you")

Ouput:

Good afternoon

2.0

Division by zero is not possible

Thank you

Exception:

An exception is on error, which can occur during runtime and which can be handled by the programmer. That means if programmer can guess an error in the program and he can avoid the abnormal termination by using try..except keywords.

Types of exceptions

1.   Predefined exception (built in exceptions)

2.   User defined exceptions

Predefined exception are represented as classes.

Purpose Exception Handling:

To make the program more powerful (robust=strong). If we are handling the exceptions, our program/application will not terminate abnormally during execution.

Steps to handling the exceptions:

1.   As a programmer should observe the code where there may be possible of exceptions, such exceptions should be kept in side the try block.

Example:

       try:

                   10/0  #risky code

2.   We should write the corresponding exception class name with except keyword. This step is called handling the exception

Ex: except for DivisionByZero:

                   Any message

3.    finally, this keyword is used to clean up the code example closing the files.

Whenever we write the statements in side the finally block, those statements will be executed irrespective of the exceptions.

The above 3 steps are called the exception handling.

Syntax:

try:

          Risky code /Run this code

except NameOfexception:

          run this code if exceptions occur in the try block

#Example program

def concat(a,b):

    print(a+b)

try:

    concat("hyd",25)

    print("good morning")

except TypeError:

    print("Only strings can be concatinated but not one string, one number")

"""output:

Case1

Only strings can be concatenated but not one string, one number

>>>

Case2: If you want to execute the statement irrespective of exception, use finally block

def concat(a,b):

    print(a+b)

try:

    concat("hyd",25)#exception raised

except TypeError:

    print("Only strings can be concatinated but not one string, one number")

finally:

    print("good morning")

"""output:

Only strings can be concatenated but not one string, one number

good morning

Case3: exception can be more than one but try should be only one

def concat(a,b):

    print(a+b)

try:

    concat("hyd",25)#exception raised

    print(10/0)

except TypeError:

    print("Only strings can be concatinated but not one string, one number")

except ZeroDivisionError:

    print("Division by zero is not possible")

finally:

    print("good morning")

"""output:

Case2

Only strings can be concatenated but not one string, one number

good morning

Related video: https://youtu.be/oC6v7WLzZFw

Next: https://youtu.be/dq9W6ig91QQ

Exception Handling part 2

Prev:Exceptions:
https://youtu.be/TeVaBIo-WQo