else block with try-except and nested try..except

try:
print("outer try block")
try:
print("inner try block")
print(2/0)
except ZeroDivisionError:
print("inner except block")
finally:
print("inner finally block")
except:
print("outer except block")
finally:
print("outer finally block")



output:

outer try block
inner try block
inner except block
inner finally block
outer finally block
We can take try-except-finally blocks inside try or except or finally blocks it is called nesting exception handling.

Generally risky code we have to take inside outer try block and too much risky code we have to take inside inner try block.
· Inside inner try block if an exception raised then except block is responsible to handle. If it unable to handle then outer except block is responsible to handle.

Syntax:

try:
……
……
try:
……..
………
except:
……..
………
except:
……
……
#example program on nested try-except finally block
try:#outer try block
print("statement1")
print(4/2)#statement2 5.0
print(10/5)#statement3 5.0
try: #inner try block
a=int(input("enter a value ")) #4
b=int(input("enter b value ")) #"two"
print("statement 4")
print(a/b)#statement 5 #exception is raised
print("statement 6")
except ValueError:#inner exception block
print("enter int only")#statement 7
finally:#inner finally block
print("statement 8")
print("statement 9")
except ZeroDivisionError: #outer except block
print("Zero Division is not possible")#statement 10
finally:
print("statement 11")
print("statement 12")

output:

statement1
2.0
2.0
enter a value 4
enter b value 0
statement 4
statement 8
statement 9
Zero Division is not possible
statement 11
statement 12



case 2:
statement1
2.0
2.0
enter a value 4
enter b value two
enter int only
statement 8
statement 9
statement 11
statement 12
else block with try-except finally block

example progrm on else block with try-except finally block
try:
a=int(input("enter a value "))
b=int(input("enter b value "))
print("hi")
print(a/b)
except ZeroDivisionError:
print("except block")
else:
print("else block")
finally:
print("finally block")
output:
Case 1:
enter a value 2
enter b value 1
hi
2.0
else block
finally block

case 2:
enter a value 4
enter b value 0
hi
except block
finally block

We can use else block with try-except finally blocks. Else block will be executed if and only if there are no exception inside try block.
Syntax:
try:
Risky code:
except:
It executes if any exception occur in the try block
else:
It executes if there is no exception in the try block
finally:
It executes always
Note:
1. For every else block, except block is mandatory.
Example:
try:
a=int(input("enter a value "))
b=int(input("enter b value "))
print("hi")
print(a/b)
else: #Error
print("else block")
2. Order of try-except-else-finally is important
3. Without try block, we can not write finally block

Example:

try:

….

finally:

……