Else & Finally In Try Except

NITIN GUPTA NITIIN GUPTA January 28, 2022

try and except block:

In the try block, we write the code in which an exception might occur, and in except block, we write the code as a result if an exception occurs. This could either be a print statement or the error itself. If no exception occurs, the except block will not execute. The purpose of try and except is to keep the program running either an error or exception occurs. In simple programs, if an error occurs, the program stops its execution and displays the error onto the screen. We can show the error as a string onto the screen by using try and except, and the program could continue its execution after that. For further explanation, you can give Tutorial #24 a watch or read the description given below.

Figure1: try and except in Python

else keyword:-

Now moving on to the else keyword. We use an else keyword to print something in cases where no exception occurs. Suppose that an exception occurred, and the except block is printing the error; likewise, if the exception does not occur, we can print a statement that no error occurred, using an else keyword. Syntax of using else with try and except block is:

try:
    #Run this code
except Exception as error:
    #Execute this code when there is an exception
else:
    #No Exception. Run this code

Note: An else will only run in the case where no exception occurs.

For Example:-

def divide(a, b):
    try:
        print(f'{a}/{b} is {a / b}')
    except ZeroDivisionError as e:
        print(e)
    else:
        print("No Exception")
divide(1, 2)

Output:-

 1/2 is 0.5
No Exception

finally:-

Now the last keyword for this tutorial, i.e., finally, will run in either case. It is also known as code cleaner because it will perform its action, either an exception occurs or not. We write such commands in the finally part of the code that we want to execute, even an exception occurs or not. It is mostly used to clean resources or close files.

try:
    #Run this code
except Exception as error:
    #Execute this code when there is an exception
else:
   #No Exception. Run this code
finally:
   #Always run this code

Now, in cases where all the four keywords are being used simultaneously, which will run and which will not, can easily be understood by the table below:

Try	Not running	Running
Except	Will run	Will not run
Else	Will not run	Will run
Finally	Will run	Will run

Summing Up

After seeing the difference between these four keywords, we learned about various ways to handle exceptions in Python. In this tutorial, so studied that:

In the try block, all the statements are executed until an exception occurs.
Except block is used to catch and handle the exception(s) that occurs during the execution of the try block.
Else block runs only when no exceptions occur in the execution of the try block.
Finally block always runs; either an exception occurs or not.

This tutorial ends here, and I will see you in the next tutorial. Till then, keep coding and keep learning.

Code as described/written in the video


f1 = open("harry.txt")

try:
    f = open("does2.txt")

except EOFError as e:
    print("Print eof error aa gaya hai", e)

except IOError as e:
    print("Print IO error aa gaya hai", e)

else:
    print("This will run only if except is not running")

finally:
    print("Run this anyway...")
    # f.close()
    f1.close()

print("Important stuff")

python