With the help of try, catch and finally statements, we can handle the exceptions in python programming. Lot of inbuilt exception are available in python which are raised if the program encounters an error

Built-In Exceptions

Below are the list of inbuilt exception which occurs at runtime due to logical errors

Exception Reason for exception
Assertion Error occurs during the failure of assert statements
Attribute Error occurs during the failure of attribute assignment
EOF Error occurs when the input function reaches the end of file condition
Floatingpoint Error occurs during the failure of floating point operations
GeneratorExit Error occurs if the closed method is called in generator
Import Error occurs if the imported module is not found
KeyError Error occurs during the failure of founding key in given dict
KeyInterrupt Error occurs if the console receives delete or ctrl+c commands
Memory Error occurs if the memory exceeds the limit
Name Error occurs if the variable is not available in the given scope
NotImplemented Error occurs if the class not implemented the abstract methods
OS Error occurs during the system related failures
Overflow Error occurs during the failure to represent large arithmetic operation
Reference Error occurs during the garbage collected referent access by a week reference proxy
Runtime Error occurs during the occurrence of unidentified exception
Stopiteration Error occurs when the iterator function not having any other items to iterate
Syntax Error occurs during the error in program syntax
Indentation Error occurs due to incorrect indentation
Tab Error occurs due to inconsistent tabs or spaces in indentation
System Error occurs due to the internal error faced by interpreter
System Exit occurs due to sys.exit function
Type Error occurs due to the incorrect object type
Unboundlocal Error occurs due to the missing of value for the given variable in a function
Unicode Error occurs due to the error in unicode related encoding and decoding
UnicodeEncode Error occurs due to the error in unicode related encoding
UnicodeDecode Error occurs due to the error in unicode related decoding
UnicodeTranslate Error occurs due to the error in unicode related translating
Value Error occurs due to the improper value for the passed arguments with correct type
ZeroDivision Error occurs due to zero value in division or modulo operation's second operand

Try and Except clause

The major functionality which can raise exception should be declare inside try statement and the code which handles the raised exception should be declare inside the except clause like the below sample program

#Exception Handling
num1 = 10
num2 = 0
try:
    result = num1//num2
except:
    print("Exception occurs during division operation")

Output

Exception during division operation

Try and Multiple Except clause

Its not a good practice the exception in very general way like the above program. We should handle the exception based on the type of exception raises like the below programs

Program 1: Handling Zero Division Exception

#Handling Zero Division Exception
num1 = 10
num2 = 0
try:
    result = num1//num2
except ZeroDivisionError:
    print("The second operand value shouldn't be zero of division operation")
except TypeError:
    print("The division operation cannot be perform for non integer type objects")
except Exception as E:
    print("Exception occurs during division operation")

Output

The second operand value shouldn't be zero of division operation

Program 2: Handling invalid type Exception

#Handling invalid type Exception
num1 = 10
num2 = "0"
try:
    result = num1//num2
except ZeroDivisionError:
    print("The second operand value shouldn't be zero of division operation")
except TypeError:
    print("The division operation cannot be perform for non integer objects")
except Exception as E:
    print("Exception occurs during division operation")

Output

The division operation cannot be perform for non integer objects

Program 3: Handling General Exceptions

#Handling general Exception
num1 = 10
try:
    result = num1//num2
except ZeroDivisionError:
    print("The second operand value shouldn't be zero of division operation")
except TypeError:
    print("The division operation cannot be perform for non integer objects")
except Exception as E:
    print("Exception occurs during division operation")

Output

Exception occurs during division operation

Try, Except and Else clause

After the successful execution of try statement, if we want to execute some other code that can be handle in else clause. If no exception occurs in execution, else clause block executes by the interpreter

#Else clause
num1 = 10
num2 = 5
try:
    result = num1//num2
except ZeroDivisionError:
    print("The second operand value shouldn't be zero of division operation")
except TypeError:
    print("The division operation cannot be perform for non integer objects")
except Exception as E:
    print("Exception occurs during division operation")
else:
    print(result)

Output

2

Try, Except and Finally clause

Finally clause executes for both successful and exceptional cases. Usually it uses for cleanup the resources like the below program

Program 1: Finally clause - Successful scenario

#Finally clause
num1 = 10
num2 = 2
try:
    result = num1//num2
    print(result)
except ZeroDivisionError:
    print("The second operand value shouldn't be zero of division operation")
except TypeError:
    print("The division operation cannot be perform for non integer objects")
except Exception as E:
    print("Exception occurs during division operation")
finally:
    del num1
    del num2
    print("Finally clause Executed")

Output

5
Finally clause Executed

Program 2: Finally clause - Exception scenario

#Finally clause
num1 = 10
num2 = 0
try:
    result = num1//num2
    print(result)
except ZeroDivisionError:
    print("The second operand value shouldn't be zero of division operation")
except TypeError:
    print("The division operation cannot be perform for non integer objects")
except Exception as E:
    print("Exception occurs during division operation")
finally:
    del num1
    del num2
    print("Finally clause Executed")

Output

The second operand value shouldn't be zero of division operation
Finally clause Executed
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