4. Basic Error Handling (`try` / `except`)

Used to handle runtime errors without crashing the program.

Basic Syntax

try:
    # risky code
except:
    # runs if error occurs

Example

try:
    print(10 / 0)
except:
    print("Cannot divide by zero")

Output

Cannot divide by zero

Catch Specific Exceptions

try:
    number = int("abc")
except ValueError:
    print("Invalid number")

Multiple Exceptions

try:
    x = 10 / 0
except ZeroDivisionError:
    print("Division Error")
except ValueError:
    print("Value Error")

`else`

Runs only if no exception occurs.

try:
    x = 10 / 2
except ZeroDivisionError:
    print("Error")
else:
    print("Success")

Output

Success

`finally`

Always executes.

try:
    print(10 / 2)
except:
    print("Error")
finally:
    print("Finished")

Output

5.0
Finished

Raising Exceptions

age = -1

if age < 0:
    raise ValueError("Age cannot be negative")

Common Built-in Exceptions

Exception	Description
`ValueError`	Wrong value type
`TypeError`	Wrong data type
`NameError`	Variable not defined
`IndexError`	Invalid list index
`KeyError`	Invalid dictionary key
`ZeroDivisionError`	Division by zero
`FileNotFoundError`	File not found
`AttributeError`	Invalid object attribute

Quick Revision

Error Handling

try → Code that may fail.
except → Handle exceptions.
else → Runs when no exception occurs.
finally → Always runs.
raise → Manually throw an exception.
Catch specific exceptions whenever possible instead of using a bare except.

Day 1

Day 2

Python Error Handling

4. Basic Error Handling (`try` / `except`)

Basic Syntax

Example

Catch Specific Exceptions

Multiple Exceptions

`else`

`finally`

Raising Exceptions

Common Built-in Exceptions

Quick Revision

Error Handling

​4. Basic Error Handling (try / except)

​Basic Syntax

​Example

​Catch Specific Exceptions

​Multiple Exceptions

​else

​finally

​Raising Exceptions

​Common Built-in Exceptions

​Quick Revision

​Error Handling

4. Basic Error Handling (`try` / `except`)

Basic Syntax

Example

Catch Specific Exceptions

Multiple Exceptions

`else`

`finally`

Raising Exceptions

Common Built-in Exceptions

Quick Revision

Error Handling