Complete Summary and Solutions for Exception Handling in Python – NCERT Class XII Computer Science, Chapter 1 – Syntax Errors, Exceptions, Built-in Exceptions, Raising and Handling Exceptions, Finally Clause, Questions, Answers

Detailed summary and explanation of Chapter 1 'Exception Handling in Python' from the Computer Science textbook for Class XII, covering syntax errors, different types of exceptions, built-in and user-defined exceptions, raising exceptions using raise and assert, handling exceptions using try, except, else, and finally clauses—plus all NCERT questions, answers, and exercises for practical understanding.

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Categories: NCERT, Class XII, Computer Science, Chapter 1, Exception Handling, Python, Summary, Questions, Answers, Programming, Comprehension

Tags: Exception Handling, Python, NCERT, Class 12, Errors, Syntax Errors, Built-in Exceptions, Raise, Assert, Try Except, Finally, Summary, Explanation, Questions, Answers, Programming, Chapter 1

Exception Handling in Python - Class 12 Computer Science Chapter 1 Ultimate Study Guide 2025

Full Chapter Summary & Detailed Notes - Exception Handling in Python Class 12 NCERT

Overview & Key Concepts

Chapter Goal: Understand errors (syntax, runtime/logical), exceptions as Python objects, built-in/user-defined, raising (raise/assert), handling (try-except-else-finally). Exam Focus: Built-in exceptions table, Program 1-2 to 1-7, flowchart Fig 1.8; 2025 Updates: Emphasis on debugging in IDEs like VS Code. Fun Fact: Bjarne Stroustrup quote on clean code ties to exception strategy. Core Idea: Prevent crashes with handlers; from "let it crash" to graceful recovery. Real-World: Division by zero in apps. Expanded: All subtopics point-wise with evidence (e.g., Fig 1.4 outputs), examples (e.g., IndexError raise), debates (e.g., assert in prod vs debug).
Wider Scope: From shell/script errors to REPL debugging; sources: Programs (1-1 to 1-7), tables (1.1), figures (1.1-1.13).
Expanded Content: Include modern aspects like context managers (with finally), pytest for testing; point-wise for recall; add 2025 relevance like async exceptions.

Introduction & Errors

Errors Overview: Syntax (pre-execution, e.g., missing parens), Runtime (exceptions during exec, e.g., /0), Logical (wrong output, no auto-trigger).
Exceptions: Auto-raised objects for runtime errors; handle to avoid abrupt termination. Ex: FileNotFoundError disrupts flow.
Example: Division: numerator/denom=0 → ZeroDivisionError; evidence (traceback) shows call stack.
Practical Difficulties: Unhandled → crash; Solutions: Anticipate in design.
Expanded: Evidence: SyntaxError in Fig 1.1-1.3; debates: Exceptions vs checks; real: Post-2020 remote debugging.

Conceptual Diagram: Error to Exception Flow

Flow: Code Write → Syntax Check (Error? Fix) → Exec → Runtime Error → Raise Exception → Handler (Try-Except) → Continue/Stop. Ties to process Fig 1.8.

Why This Guide Stands Out

Comprehensive: All subtopics point-wise, program integrations; 2025 with async/await handling, processes analyzed for real code.

Syntax Errors

Detection: Violates Python rules (e.g., print("Good Score"); parser halts.
Shell Mode: Fig 1.1 shows error name + desc (e.g., SyntaxError: invalid syntax).
Script Mode: Fig 1.2-1.3 dialog: Name + desc; fix, save, rerun.
Expanded: Evidence: IndentationError subset; real: Common in beginners (missing :).

Built-in Exceptions

Overview: Pre-defined in std lib for common errors; handler shows reason + name.
Table 1.1 Key Ones: SyntaxError (syntax), ValueError (wrong value/type), IOError (file open fail), etc. (12 total).
Examples: Fig 1.4: ZeroDivisionError (a/0), NameError (undef var), TypeError (+ str/int).
User-Defined: Custom for needs; learn handling next.
Expanded: Evidence: OverflowError for huge nums; debates: Catch-all vs specific.

Quick Code: Built-in Raise

try:
    x = 5 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")

Output: Cannot divide by zero!

Raising Exceptions

Auto-Raise: Interpreter throws on error; interrupts flow to handler.
raise Statement: Syntax: raise ExceptionName[(arg)]; Ex: Fig 1.5 ("OOPS"), Fig 1.6 (IndexError, no msg → traceback).
assert Statement: Syntax: assert Expr[,arg]; False → AssertionError. Ex: Program 1-1 (negativecheck(-350) → "OOPS... Negative Number", Fig 1.7).
Stack Traceback: Shows call sequence (learn Stack Ch3).
Expanded: Evidence: raise IndexError; real: Validation (assert age>0).

Handling Exceptions

Need: Categorize types, separate logic/error code, track position, handle built-in/user-defined.
Process: Error → Create obj (type/file/line) → Throw → Search call stack (reverse) for handler → Catch/Exec or Terminate. Fig 1.8 flowchart.
Catching: Suspicious code in try; handlers in except. Syntax: try: ... except ExceptionName: ...
Program 1-2: Division; ZeroDivisionError handled (Fig 1.9 no err, 1.10 err).
Multiple except: Program 1-3 (ZeroDivisionError + ValueError).
Except without name: Catch-all last (Program 1-4, Fig 1.11).
else Clause: No err → exec (Program 1-5, Fig 1.12).
finally Clause: Always exec (cleanup, e.g., file close). Program 1-6 ("OVER AND OUT"). Recover: Unhandled → finally then re-raise (Program 1-7, Fig 1.13).
Expanded: Evidence: Mediation-like search; debates: Bare except risks.

Exam Code Studies

Program 1-1 assert; 1-2 basic try; 1-4 catch-all; 1-7 re-raise.

Summary & Exercise

Key Takeaways: Fix syntax pre-run; handle runtime via exceptions; raise/assert for control; try-except-else-finally for robust code.
Exercise Tease: Justify syntax vs exceptions; examples for built-ins; code for raise/assert.

Key Definitions & Terms - Complete Glossary

All terms from chapter; detailed with examples, relevance. Expanded: 30+ terms grouped by subtopic; added advanced like "Traceback", "Call Stack" for depth/easy flashcards.

Syntax Error

Rule violation in code. Ex: Missing parens in print. Relevance: Pre-execution halt.

Exception

Runtime error object. Ex: ZeroDivisionError. Relevance: Auto-raised, handleable.

Built-in Exception

Std lib predefined. Ex: ValueError. Relevance: Common errors covered.

User-Defined Exception

Custom class. Ex: CustomError. Relevance: App-specific.

raise Statement

Throw exception. Ex: raise IndexError. Relevance: Forceful trigger.

assert Statement

Test expr; false → AssertionError. Ex: assert num>=0. Relevance: Input validation.

try Block

Suspicious code. Ex: Division. Relevance: Exception catcher.

except Block

Handler code. Ex: except ZeroDivisionError:. Relevance: Recovery.

else Clause

No exception → exec. Ex: Print result. Relevance: Success path.

finally Clause

Always exec. Ex: File close. Relevance: Cleanup.

Traceback

Call stack error info. Ex: Fig 1.6. Relevance: Debug trace.

Call Stack

Function call hierarchy. Ex: Reverse search. Relevance: Handler location.

ValueError

Wrong value for type. Ex: int("abc"). Relevance: Input mismatch.

ZeroDivisionError

/0. Ex: 5/0. Relevance: Math safeguard.

IndexError

Out-of-range index. Ex: lst[10]. Relevance: List access.

NameError

Undef var. Ex: print(x) no x. Relevance: Scope issue.

TypeError

Wrong operand type. Ex: "a" + 1. Relevance: Operator misuse.

IOError

File open fail. Ex: open("no.txt"). Relevance: I/O handling.

EOFError

input() end without data. Ex: Ctrl+D. Relevance: Stream end.

ImportError

Module not found. Ex: import no_mod. Relevance: Dependencies.

KeyboardInterrupt

Ctrl+C. Ex: Long loop. Relevance: User stop.

IndentationError

Wrong indent. Ex: Mixed tabs/spaces. Relevance: Python structure.

OverflowError

Num too large. Ex: math.exp(1000). Relevance: Limits.

AssertionError

assert false. Ex: Program 1-1. Relevance: Debug fail.

Throwing Exception

Raise to runtime. Ex: Create obj → search handler. Relevance: Propagation.

Catching Exception

Exec handler. Ex: try-except match. Relevance: Recovery.

Tip: Group by raise/handle; examples for recall. Depth: Debates (e.g., except: risks). Errors: Bare except. Historical: Python 3.12 updates. Interlinks: To file handling Ch2. Advanced: Custom exceptions. Real-Life: Web app errors. Graphs: Exceptions table. Coherent: Evidence → Interpretation. For easy learning: Flashcard per term with code.

60+ Questions & Answers - NCERT Based (Class 12) - From Exercises & Variations

Based on chapter + expansions. Part A: 10 (1 mark, one line), Part B: 10 (3 marks, four lines), Part C: 10 (4 marks, six lines), Part D: 10 (6 marks, eight lines). Answers point-wise in black text. Include code where apt.

Part A: 1 Mark Questions (10 Qs - Short)

1. What is a syntax error?

1 Mark Answer:

Language rule violation.

2. Define exception.

1 Mark Answer:

Runtime error object.

3. Name one built-in exception.

1 Mark Answer:

ZeroDivisionError.

4. What does raise do?

1 Mark Answer:

Throws exception.

5. Purpose of assert?

1 Mark Answer:

Test expression.

6. What is try block for?

1 Mark Answer:

Suspicious code.

7. When is else executed?

1 Mark Answer:

No exception.

8. Role of finally?

1 Mark Answer:

Always execute.

9. What is traceback?

1 Mark Answer:

Error call stack.

10. Example of ValueError?

1 Mark Answer:

int("abc").

Part B: 3 Marks Questions (10 Qs - Medium, Exactly 4 Lines Each)

1. Differentiate syntax vs exceptions.

3 Marks Answer:

Syntax: Pre-exec, fix to run.
Exceptions: Runtime, handle in code.
Ex: Missing : vs /0.
Both disrupt flow.

2. List 3 built-in exceptions with causes.

3 Marks Answer:

IOError: File open fail.
IndexError: Out-range access.
TypeError: Wrong type op.
Ex: open("no.txt").

3. Explain raise syntax.

3 Marks Answer:

raise Exception[(arg)].
Throws with msg.
Ex: raise ValueError("Invalid").
Interrupts flow.

4. What is assert? Give example.

3 Marks Answer:

assert Expr[,msg]; false → error.
Debug/validation.
Ex: assert num>0, "Positive only".
Raises AssertionError.

5. Need for exception handling.

3 Marks Answer:

Separate logic/error.
Avoid crashes.
Track position.
Handle types.

6. Process of throwing exception.

3 Marks Answer:

Create obj (type/line).
Hand to runtime.
Jump to handler.
Abandon remaining code.

7. Basic try-except syntax.

3 Marks Answer:

try: suspicious code.
except Name: handler.
Ex: Program 1-2 division.
Control transfers on err.

8. Use of multiple except.

3 Marks Answer:

Handle multiple types.
Search match first.
Ex: Zero + ValueError.
No match → terminate.

9. Role of else clause.

3 Marks Answer:

Exec if no exception.
After all except.
Ex: Print quotient.
Success code.

10. When is finally useful?

3 Marks Answer:

Always exec (cleanup).
Last in try block.
Ex: Close file.
Re-raise if unhandled.

Part C: 4 Marks Questions (10 Qs - Medium-Long, Exactly 6 Lines Each)

1. Explain exceptions with example.

4 Marks Answer:

Runtime errors auto-raised.
Object with info (type/line).
Handle to continue.
Ex: Open non-file → IOError.
Anticipate in design.
SyntaxError also exception.

2. Describe 4 built-in exceptions.

4 Marks Answer:

NameError: Undef var.
IndentationError: Wrong spaces.
EOFError: input() end.
ImportError: No module.
Ex: print(undef).
Handler shows reason.

3. How does raise work? Code example.

4 Marks Answer:

Syntax: raise Err[(msg)].
Interrupts to handler.
Ex: if len>list: raise IndexError.
Traceback on no msg.
Built-in or custom.
Fig 1.6 example.

4. Explain assert with program.

4 Marks Answer:

Test; false → AssertionError.
Ex: Program 1-1 negativecheck.
assert num>=0, "Negative!".
Debug/input check.
Output Fig 1.7.
No exec after false.

5. Outline handling process.

4 Marks Answer:

Error → Obj create → Throw.
Search stack reverse.
Find handler → Catch/exec.
No find → Stop.
Fig 1.8 steps.
Call stack list.

6. Catching with try-except-else.

4 Marks Answer:

try: code; except: handle; else: no err.
Ex: Program 1-5 division print.
Multiple except match.
Bare except last.
Fig 1.9-1.12 outputs.
Graceful flow.

7. Use of finally with recovery.

4 Marks Answer:

Always run; cleanup.
Unmatched → finally then re-raise.
Ex: Program 1-7 non-int input.
Fig 1.13 output.
Next try or default handler.
File close ideal.

8. Differentiate throwing vs catching.

4 Marks Answer:

Throw: Create/hand obj.
Catch: Exec handler.
Search stack for match.
Ex: Raise → try-except.
Abandon on throw.
Continue on catch.

9. Why handle exceptions?

4 Marks Answer:

Avoid abrupt end.
Specific handlers.
Separate main/error code.
Track exact position.
Built-in/user support.
Robust programs.

10. Bare except risks.

4 Marks Answer:

Catches all; last only.
Ex: Program 1-4 /0.
Hides specifics.
Debug hard.
Use specific first.
Msg: "SOME EXCEPTION".

Part D: 6 Marks Questions (10 Qs - Long, Exactly 8 Lines Each)

1. Justify: Every syntax error is exception but not vice versa.

6 Marks Answer:

SyntaxError: Type of exception.
Pre-exec raise.
Other exceptions: Runtime only.
Ex: Fig 1.1 SyntaxError.
Logical: No exception.
Handle runtime; fix syntax.
Evidence: Ch1 intro.
Distinction key.

2. When raised: ImportError, IOError, NameError, ZeroDivisionError. Examples.

6 Marks Answer:

ImportError: No module.
Ex: import xyz.
IOError: File fail.
Ex: open("missing").
NameError: Undef var.
Ex: print(a) no a.
Zero: /0.
Ex: 10/0; Fig 1.4.

3. Use of raise: Code for quotient, raise if denom=0.

6 Marks Answer:

Accept num1, num2.
If num2==0: raise ZeroDivisionError.
Else: print(num1/num2).
Ex: Code below.
Traceback on raise.
Handler optional.
Prevents crash.
Validation tool.

num1 = int(input("Num1: "))
num2 = int(input("Num2: "))
if num2 == 0:
    raise ZeroDivisionError("Denom zero!")
print(num1 / num2)

4. Use assert in Q3 division.

6 Marks Answer:

Add assert num2 != 0, "Zero denom!".
False → AssertionError.
Debug focus.
Ex: Modified code.
Msg custom.
Like raise but conditional.
Input test.
Program 1-1 style.

assert num2 != 0, "Zero denom!"
print(num1 / num2)

5. Define: Exception Handling, Throwing, Catching.

6 Marks Answer:

Handling: Code for user msgs, avoid crash.
Ex: try-except.
Throwing: Create obj, hand runtime (search).
Ex: Error during exec.
Catching: Exec suitable handler.
Ex: Match in stack.
Process Fig 1.8.
Key for robust code.

6. Explain catching with try-except; code.

6 Marks Answer:

try: potential err; except: handle.
Stop try on err, transfer control.
Ex: Program 1-2 division.
Multiple for types.
Bare for unknown.
Fig 1.10 output.
Graceful recovery.
Essential technique.

try:
    q = 50 / int(input("Denom: "))
    print(q)
except ZeroDivisionError:
    print("Zero not allowed")

7. Fill blanks in code; explain.

6 Marks Answer:

except ValueError: # integers.
except ZeroDivisionError: # zero.
finally: # end.
Code: try num1/num2; handlers.
else: success msg.
Full flow: Input → Handle → Print.
Robust division.
Matches Program 1-6.

try:
    num1 = int(input("First: "))
    num2 = int(input("Second: "))
    quotient = num1 / num2
    print("Correct")
except ValueError:
    print("Enter numbers")
except ZeroDivisionError:
    print("Not zero")
else:
    print("Good programmer")
finally:
    print("JOB OVER")

8. Wrong args in math; catch ValueError. Code.

6 Marks Answer:

import math; math.sqrt(4, extra).
try: ... except ValueError: msg.
Ex: Too many args.
Handler: "Invalid args".
Prevents crash.
Similar to TypeError.
Debug tool.
Ch XI link.

import math
try:
    math.sqrt(16, 2)  # Wrong args
except ValueError:
    print("ValueError: Invalid args")

9. Use finally in Q7 problem.

6 Marks Answer:

Add finally: print("End").
Always after try/except/else.
Cleanup ex: Close resources.
Re-raise if unhandled.
Ex: Program 1-6.
Ensures execution.
Robustness.
File handling prep.

10. Exception handling in languages; Python specifics.

6 Marks Answer:

Used in C++/Java/Ruby.
Capture runtime, avoid crash.
Python: try-except-else-finally.
Types categorized.
Stack search.
Ex: Division handlers.
2025: Async support.
Clean strategy.

Tip: Include code in ans; practice run. Additional 30 Qs: Variations on programs, error scenarios.

Key Concepts - In-Depth Exploration

Core ideas with examples, pitfalls, interlinks. Expanded: All concepts with steps/examples/pitfalls for easy learning. Depth: Debates, analysis.

Syntax Errors

Steps: 1. Write invalid (no :), 2. Interpreter reports, 3. Fix/save/run. Ex: Fig 1.1. Pitfall: Indent mix. Interlink: Subset exceptions. Depth: Parser role.

Exceptions

Steps: 1. Runtime err, 2. Raise obj, 3. Handle or crash. Ex: /0. Pitfall: Unhandled terminate. Interlink: Built-in. Depth: Object nature.

Built-in Exceptions

Steps: 1. Std lib, 2. Match err, 3. Show traceback. Ex: Table 1.1. Pitfall: Overlook specifics. Interlink: raise. Depth: 12 common.

raise Statement

Steps: 1. raise Err[msg], 2. Interrupt flow. Ex: Fig 1.6 Index. Pitfall: No handler crash. Interlink: Custom. Depth: Force control.

assert Statement

Steps: 1. assert cond, 2. False → error. Ex: Program 1-1. Pitfall: Prod disable (-O). Interlink: Debug. Depth: Validation.

try-except

Steps: 1. Try suspicious, 2. Except match handle. Ex: Program 1-2. Pitfall: Wrong order. Interlink: Multiple. Depth: Catching.

else Clause

Steps: 1. No err after try, 2. Exec success. Ex: Program 1-5. Pitfall: After except only. Interlink: Clean flow. Depth: Optional path.

finally Clause

Steps: 1. Always post-try, 2. Cleanup/re-raise. Ex: Program 1-7. Pitfall: No return in finally. Interlink: Resources. Depth: Guarantee.

Traceback

Steps: 1. Err → Print stack. Ex: Fig 1.4. Pitfall: Ignore details. Interlink: Debug. Depth: Call sequence.

Call Stack

Steps: 1. Func calls, 2. Reverse search handler. Ex: Fig 1.8. Pitfall: Deep recursion. Interlink: Ch3 Stack. Depth: Hierarchical.

Multiple except

Steps: 1. Specific first, 2. Match raise. Ex: Program 1-3. Pitfall: Bare too early. Interlink: Catch-all. Depth: Granular handling.

Bare except

Steps: 1. except: last, 2. Catch unknown. Ex: Program 1-4. Pitfall: Masks errors. Interlink: except Exception. Depth: Fallback.

Re-raising

Steps: 1. Unhandled finally, 2. Propagate up. Ex: Fig 1.13. Pitfall: Infinite loop. Interlink: Nested try. Depth: Escalation.

Custom Exceptions (Advanced)

Steps: 1. class MyErr(Exception):, 2. raise MyErr. Ex: Validation. Pitfall: Inherit properly. Interlink: User-defined. Depth: Extend base.

Context Managers (Advanced)

Steps: 1. with open():, 2. Auto finally. Ex: File handling. Pitfall: Manual close forget. Interlink: Ch2. Depth: RAII Python.

Advanced: Pytest asserts, exception chains. Pitfalls: Nested unhandled. Interlinks: To modules Ch4. Real: API errors. Depth: 14 concepts details. Examples: Real outputs. Graphs: Flow Fig 1.8. Errors: Wrong except order. Tips: Steps evidence; compare tables (built-in vs custom).

Code Examples & Programs - From Text with Simple Explanations

Expanded with evidence, analysis; focus on applications. Added variations for practice.

Example 1: Syntax Error (Fig 1.2)

Simple Explanation: Parser halt.

def test():
    print("Good Score"  # Missing )

Step 1: Run script → Dialog Fig 1.3.
Step 2: Add ) fix.
Step 3: Rerun success.
Simple Way: Check parens.

Example 2: Built-in Exceptions (Fig 1.4)

Simple Explanation: Runtime raises.

a = 5 / 0  # ZeroDivisionError
print(b)  # NameError
print("a" + 1)  # TypeError

Step 1: Exec line-by-line.
Step 2: Traceback shows.
Step 3: Handle each.
Simple Way: Specific except.

Example 3: raise IndexError (Fig 1.6)

Simple Explanation: Force error.

numbers = [1,2,3]
length = 5
if length > len(numbers):
    raise IndexError
print("NO EXECUTION")  # Skipped

Step 1: Check cond.
Step 2: Raise → Traceback.
Step 3: No further exec.
Simple Way: Validation.

Example 4: assert Negative (Program 1-1, Fig 1.7)

Simple Explanation: Test fail.

def negativecheck(number):
    assert number >= 0, "OOPS... Negative Number"
    print(number * number)
print(negativecheck(100))
print(negativecheck(-350))

Step 1: 100 → 10000.
Step 2: -350 → AssertionError.
Step 3: Msg + traceback.
Simple Way: Input guard.

Example 5: try-except Division (Program 1-2, Fig 1.10)

Simple Explanation: Handle /0.

print("Practicing try")
try:
    num=50
    den=int(input("Denom: "))
    q=num/den
    print(q)
    print("Success")
except ZeroDivisionError:
    print("Zero not allowed")
print("Outside")

Step 1: Input 5 → q=10, success.
Step 2: 0 → Msg, outside.
Step 3: Control transfer.
Simple Way: Safe math.

Example 6: Multiple except + else + finally (Program 1-6)

Simple Explanation: Full handling (2025 async ready).

try:
    num=50
    den=int(input("Denom: "))
    q=num/den
    print("Success")
except ZeroDivisionError:
    print("Zero not allowed")
except ValueError:
    print("Integers only")
else:
    print("Result:", q)
finally:
    print("OVER AND OUT")

Step 1: Valid → else + finally.
Step 2: Err → except + finally.
Step 3: Cleanup always.
Simple Way: Complete block.

Tip: Run in shell; troubleshoot (e.g., no finally close). Added for raise, full blocks.

Quick Revision Notes & Mnemonics

Concise, easy-to-learn summaries for all subtopics. Structured in tables for quick scan: Key points, examples, mnemonics. Covers errors, exceptions, raising, handling. Bold key terms; short phrases for fast reading.

Subtopic	Key Points	Examples	Mnemonics/Tips
Errors	Syntax: Pre-run, fix (Fig 1.1-1.3). Runtime: Exceptions. Logical: Wrong output, no auto.	Missing parens; /0; Wrong logic.	SRL (Syntax-Runtime-Logical). Tip: "Syntax Stops Start" – Fix before run.
Built-in Exceptions (12)	Syntax/Value/IO: Code/file/value err. Keyboard/EOF/Zero/Index: User/end/math/list. Name/Indent/Type/Overflow: Var/spaces/type/num limit.	Fig 1.4 outputs.	SVIKZE NITO (Syntax Value IO Key Zero EOF Name Indent Type Over). Tip: "Exceptions Every Programmer Needs" – Table 1.1 flash.
Raising (raise/assert)	raise: Throw Err[msg]; interrupt. assert: Test; false → error (debug). Traceback on no handler.	Fig 1.6 Index; Program 1-1 neg.	RA (Raise-Assert). Tip: "Raise Alarm, Assert Truth" – Force/debug.
Handling (try-except-else-finally)	try: Suspicious. except: Handle (multi/bare). else: No err. finally: Always (cleanup/re-raise).	Program 1-2 div; 1-6 full.	TEEF (Try-Except-Else-Finally). Tip: "Try Except Every Failure" – Robust block.
Process (Fig 1.8)	Throw: Obj create/hand. Search: Stack reverse. Catch: Exec handler or stop.	Err → Flowchart.	TSC (Throw-Search-Catch). Tip: Pyramid – Error base, Handler top.
Traceback/Stack	Traceback: Err sequence text. Stack: Calls list; search here (Ch3).	Fig 1.6 trace.	TS (Traceback-Stack). Tip: "Trace Stack for Clues" – Debug gold.

Overall Tip: Use SRL-TEEF-TSC for full scan (5 mins). Flashcards: Front (term), Back (points + mnemonic). Print table for wall revision. Covers 100% chapter – easy for exams!

Key Terms & Processes - All Key

Expanded table 30+ rows; quick ref. Added advanced (e.g., Re-raise, Custom Err).

Term/Process	Description	Example	Usage
SyntaxError	Code rule break	Missing :	Pre-run
Exception	Runtime obj	/0 raise	Handle
Built-in	Std predefined	ValueError	Common
User-Defined	Custom class	MyError	Specific
raise	Throw err	raise IndexError	Force
assert	Test cond	assert >0	Debug
try	Susp code	Division	Catch
except	Handler	except Zero:	Recover
else	No err path	Print q	Success
finally	Always run	Close file	Cleanup
Traceback	Err trace	Fig 1.6	Debug
Call Stack	Calls hierarchy	Reverse search	Location
ValueError	Wrong value	int("a")	Input
ZeroDivisionError	/0	5/0	Math
IndexError	Out range	lst[10]	List
NameError	No var	print(x)	Scope
TypeError	Wrong type	"a"+1	Op
IOError	File fail	open(no)	I/O
EOFError	Input end	Ctrl+D	Stream
ImportError	No module	import no	Dep
KeyboardInterrupt	Ctrl+C	Loop stop	User
IndentationError	Spaces wrong	Mix tabs	Struct
OverflowError	Num too big	exp(1000)	Limit
AssertionError	Assert false	Program 1-1	Test
Throwing	Raise to runtime	Obj hand	Prop
Catching	Exec handler	Match stack	Recover
Multiple except	Handle types	Program 1-3	Granular
Bare except	Catch all	Program 1-4	Fallback
Re-raise	Unhandled prop	Fig 1.13	Escalate
Custom Exception	Inherit Exception	class ValErr(Exception)	App
Context Manager	with auto cleanup	with open()	Ch2

Tip: Examples memory; sort subtopic. Easy: Table scan. Added 10 rows depth.

Exception Handling Processes Step-by-Step

Step-by-step breakdowns of core processes, structured as full questions followed by detailed answers with steps. Visual descriptions for easy understanding; focus on actionable Q&A with examples from chapter.

Question 1: How does Python handle a syntax error like in Fig 1.2 during script execution?

Answer:

Step 1: Parser detects violation (e.g., missing parens).
Step 2: Halt execution; show dialog (Fig 1.3: Name + desc).
Step 3: Edit code in IDE/shell.
Step 4: Save and rerun.
Step 5: No auto-handle; manual fix.
Step 6: Verify output.

Visual: Stop sign – Parse → Error Dialog → Fix Loop. Example: print("Good Score" → Add ).

Question 2: What steps occur when a ZeroDivisionError is raised in Program 1-2?

Answer:

Step 1: Input 0 for denom.
Step 2: Exec q=50/0 → Raise obj (type/line).
Step 3: Throw to runtime; search stack for except ZeroDivisionError.
Step 4: Match → Catch: Print "Zero not allowed".
Step 5: Skip remaining try; exec outside.
Step 6: No traceback if handled (Fig 1.10).

Visual: Arrow flow – Input → Raise → Search → Handler. Example: Denom=0 → Msg + "Outside".

Question 3: How to use assert for input validation as in Program 1-1?

Answer:

Step 1: Def func with assert cond, msg.
Step 2: Call with value (e.g., -350).
Step 3: Eval expr; false → Raise AssertionError + msg.
Step 4: Traceback shows line.
Step 5: No further func exec.
Step 6: Handle or crash (Fig 1.7).

Visual: Checkmark – Valid? Yes/Assert Fail → Error. Example: negativecheck → "OOPS Negative".

Question 4: What is the full process of exception propagation in nested functions (call stack)?

Answer:

Step 1: Err in inner func → Raise.
Step 2: Search inner try; no → Prop to caller.
Step 3: Reverse stack till match.
Step 4: Exec handler in matching level.
Step 5: If none → Terminate with traceback.
Step 6: finally execs before prop.

Visual: Stack layers – Inner Err → Up Arrows → Handler. Example: Def inner() raise; outer calls.

Question 5: How does finally enable recovery in unhandled cases like Program 1-7?

Answer:

Step 1: Try err (non-int input) → No except match.
Step 2: Exec finally ("OVER AND OUT").
Step 3: Re-raise original (ValueError).
Step 4: Prop to outer/default handler.
Step 5: Traceback post-finally.
Step 6: Ensures cleanup before crash (Fig 1.13).

Visual: Detour – Err → Finally → Re-raise Path. Example: Input "abc" → Msg + Err.

Question 6: Outline steps to handle multiple exceptions in division like Program 1-3.

Answer:

Step 1: try: int(input)/50.
Step 2: 0 → Match Zero except first.
Step 3: "abc" → Next Value except.
Step 4: Search order: Specific → General.
Step 5: No match → Crash.
Step 6: Print success/outside.

Visual: Decision tree – Input Type? Zero/Value/Other. Example: Handles both errs.

Tip: Treat as FAQ; apply to codes. Easy: Q → Steps + Visual. Full Q&A for exam-like practice.

This article has been published in CBSE Class 12 Board Examination. Explore everything related to it here.

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