Exception Handling

Exception Handling :

Like other languages, python also provides the runtime errors via exception handling method with the help of try-except. Some of the standard exceptions which are most frequent include IndexError, ImportError, IOError, ZeroDivisionError, TypeError.

Example 1:

# Python program to handle simple runtime error 

a = [1, 2, 3] 
try: 
    print("Second element = %d"%(a[1]))

    # Throws error since there are only 3 elements in array 
    print("Fourth element = %d"%(a[3]) )

except IndexError: 
    print("An error occurred")

Second element = 2

An error occurred

Example 2:

# Program to handle multiple errors with one except statement 
try : 
	a = 3
	if a < 4 : 

		# throws ZeroDivisionError for a = 3 
		b = a/(a-3) 
	
	# throws NameError if a >= 4 
	print("Value of b = ", b)

# note that braces () are necessary here for multiple exceptions 
except(ZeroDivisionError, NameError): 
	print("\nError Occurred and Handled")

Error Occurred and Handled

Else Clause

Example 3:

# Program to depict else clause with try-except 

# Function which returns a/b 
def AbyB(a , b): 
	try: 
		c = ((a+b) / (a-b)) 
	except ZeroDivisionError: 
		print("a/b result in 0")
	else: 
		print(c)
	finally:
		print("success")

# Driver program to test above function 
AbyB(2.0, 3.0) 
AbyB(3.0, 3.0) 

-5.0

a/b result in 0

success

Example 4:

import sys

randomList = ['a', 0, 2]

for entry in randomList:
    try:
        print("The entry is", entry)
        r = 1/int(entry)
        break
    except:
        print("Oops!",sys.exc_info()[0],"occured.")
        print("Next entry.")
        print()
print("The reciprocal of",entry,"is",r)

The entry is a

Oops! <class 'ValueError'> occured.

Next entry.

The entry is 0

Oops! <class 'ValueError'> occured.

Next entry.

The entry is 2

The reciprocal of 2 is 0.5