try-except

The try-except block in python is used to catch and handle Exceptions. Below is the basic structure of try-except block.

try:
    statement 1
    statements which can cause error
    statement 3
except [ExceptionName]:
    code for exception handling 

• Python runs the code from try block.
• If it encounters Exception, the code execution will jump to except block. Rest of lines from try block will not be executed (statement 3 in above case).
• If no Exception occurs, try block will be executed completely and except block will be skipped.

try block:

• Block containing code in which Exception can occur.

except block:

• Block where you take necessary actions if Exception occurs.

Example:

try:
   a = int(input())
   b = int(input())
   div = a/b
   print("Division is:",div)
except ZeroDivisionError:
   print("Cannot divide by zero")
   
print("Rest of code")

This program will run perfectly if user enters non-zero for b. 

If user enters 0 for b, 'a/b' will cause ZeroDivisionError and control will go to except block.

It will print "Cannot divide by zero" message on console and rest of code will be executed. We avoided program termination here by using try-except