• Error: problem in program that stops execution (e.g., syntax mistake).
• Exception: runtime error that can be handled using try-except.
• Examples of exceptions: ZeroDivisionError, ValueError, TypeError, FileNotFoundError.

# Syntax Error example (cannot be handled by try-except)
# if True
#     print("Hello")

• ZeroDivisionError → divide by zero
• ValueError → wrong value conversion
• TypeError → wrong type operation
• IndexError → invalid index in list/tuple
• KeyError → missing key in dictionary
• FileNotFoundError → file not found

# Example
print(10 / 0)   # ZeroDivisionError

• try contains risky code.
• except handles the exception and prevents crash.

try:
    a = int(input("Enter a number: "))
    print(10 / a)
except ZeroDivisionError:
    print("Cannot divide by zero")
except ValueError:
    print("Enter a valid integer")

• Handle multiple exceptions using a tuple in one except block.

try:
    a = int(input("Enter a number: "))
    print(10 / a)
except (ZeroDivisionError, ValueError):
    print("Invalid input or division by zero")

• Use as to store error message in a variable.
• Useful for debugging/logging.

try:
    x = int("abc")
except Exception as e:
    print("Error:", e)

• finally always runs (error or no error).
• Used for cleanup like closing file, database connection, etc.

try:
    f = open("data.txt", "r")
    print(f.read())
except FileNotFoundError:
    print("File not found")
finally:
    # safe close
    try:
        f.close()
    except:
        pass

• raise is used to manually throw an exception.
• Used when input/condition is invalid.

age = int(input("Enter age: "))

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

print("Age:", age)

• Create your own exception class by inheriting from Exception.
• Use when you want meaningful errors for your project.

class InvalidMarksError(Exception):
    pass

marks = int(input("Enter marks: "))

try:
    if marks < 0 or marks > 100:
        raise InvalidMarksError("Marks must be between 0 and 100")
    print("Marks:", marks)
except InvalidMarksError as e:
    print("Custom Error:", e)