Handle Exception In Python

 

Handle Exception In Python

Simple program which throws Exception

 # program for exception handling

 number_1 = int(input("Enter number 1 : "))
 number_2 = int(input("Enter number 2 : "))

 result = number_1 / number_2
 print("result : ", result)

 #output

 Enter number 1 : 10
 Enter number 2 : 0
 Traceback (most recent call last):
   File "C:/Self_Practice_Er_M_S_Dandyan/Python/Pycharm/xml/main.py", line 6, in <module>
     result = number_1 / number_2
 ZeroDivisionError: division by zero

• Try and except block

                       It is a combination of try and except, exception thrown in statement under try, will handover to except blog

Syntax : 

Case 1

try :

----------statement1

except Exception class_name :

---------- statement related to handle part

 #program for exception handling

 try :
     number_1 = int(input("Enter number 1 : "))
     number_2 = int(input("Enter number 2 : "))

     result = number_1 / number_2
     print("result : ", result)

 except ZeroDivisionError:                   # this named except block, it will handle DIVIDE by Zero exception
     print("number_2 can not be zero")

 #Output

 Enter number 1 : 10
 Enter number 2 : 0
 number_2 can not be zero

Case 2

        try :

----------statement1

----------statement 2

except Exception class_name :

---------- statement related to handle part

except :

---------- statement related to handle part

 #program for exception handling

 try :
     number_1 = int(input("Enter number 1 : "))
     number_2 = int(input("Enter number 2 : "))

     result = number_1 / number_2
     print("result : ", result)

 except ZeroDivisionError:                   # this named default block, it will handle DIVIDE by Zero exception
     print("number_2 can not be zero")

 except :                                    # This is default except block, it will handle all type of exception
     print("Please enter a valid integer number")

Handling Exception with specific class 

 #Output

 Enter number 1 : 10
 Enter number 2 : 0
 number_2 can not be zero

Handling Exception with Default (handel all type of exception)

 #Output

 Enter number 1 : 10
 Enter number 2 : 10.25
 Please enter a valid integer number

• Try with else block

                      It is a combination of try and except with else blog, exception thrown in statement under try, will handover to except blog and then else blog will be executed only in case of no exception thrown.

Syntax : 

try :

----------statement1

----------statement 2

except Exception class_name :

---------- statement related to handle part

else :

---------- statement related to else part.

 #program for try and else block, else part will be getting executed when no exception thrown
 try :
      number_1 = int(input("Enter number 1 : "))
      number_2 = int(input("Enter number 2 : "))

      result = number_1 / number_2
      print("result : ", result)

 except ZeroDivisionError:                   # this named default block, it will handle DIVIDE by Zero exception
      print("number_2 can not be zero")

 except :                                    # This is default except block, it will handle all type of exception
      print("Please enter a valid integer number")

 else :
     print("In else block, No Exception thrown in try block ")

when exception encounter

 #Output

 Enter number 1 : 10
 Enter number 2 : 0
 number_2 can not be zero

when No-Exception encountered

 #Output

 Enter number 1 : 10
 Enter number 2 : 5
 result :  2.0
 In else block, No Exception thrown in try block 

• Try with finally block

                      It is a combination of try and except with finally blog , exception thrown in statement under try, will handover to except blog.

                        finally blog will execute in both conditions, exception thrown or not

Syntax : 

try :

----------statement1

----------statement 2

except Exception class_name :

---------- statement related to handle part

finally :

---------- statement related to final part. 

 

# program for exception handling with try and finally block

try :
     number_1 = int(input("Enter number 1 : "))
     number_2 = int(input("Enter number 2 : "))

     result = number_1 / number_2
     print("result : ", result)

except ZeroDivisionError:                   # this named default block, it will handle DIVIDE by Zero exception
     print("number_2 can not be zero")

except :                                    # This is default except block, it will handle all type of exception
     print("Please enter a valid integer number")

finally:
    print("In finally block, this block will execute and independent of exception occurance or non-occurance")

When exception occurs

 #Output

 Enter number 1 : 10
 Enter number 2 : 0
 number_2 can not be zero
 In finally block, this block will execute and independent of exception occurance or non-occurance

When no exception occurs

 #Output

 Enter number 1 : 10
 Enter number 2 : 5
 result :  2.0
 In finally block, this block will execute and independent of exception occurance or non-occurance