Testing and debugging programs

Belajar sambil bermain

Jawab soal-soal ini untuk dapat energi, lalu memancing dan menjelajah. Tanpa akun.

Untuk pendidik: slide pelajaran, catatan ulasan siap pakai untuk Testing and debugging programs (KS3 Computing, Computer Science) — gunakan dalam pelajaranmu, atau jalankan topik sebagai aktivitas kelas interaktif yang dimainkan pembelajar sebagai permainan langsung.

Catatan pelajaran

What are Bugs and Debugging?

A bug is a defect or fault in a program that causes it to behave incorrectly.
Debugging is the process of finding the root cause of a bug, and then fixing it.
The term 'bug' dates back to at least 1878, used by Thomas Edison for 'little faults and difficulties'.
A famous story from the 1940s: Grace Hopper's team found a moth in a relay, calling it the 'first actual case of a bug being found'.
Debugging can involve interactive debugging, control flow analysis, log file analysis, and using debuggers.

Debugging is a routine: reproduce, gather clues, form a hypothesis, isolate the cause, fix it, then retest.

Types of Errors

Syntax errors: mistakes in the grammar of the programming language, e.g., missing semicolon or misspelled keyword. The program won't run.
Runtime errors: occur while the program is running, e.g., dividing by zero or trying to open a file that doesn't exist.
Logic errors: the program runs but produces wrong results because the algorithm or code logic is flawed.
Error messages from the compiler or interpreter help locate syntax errors; runtime errors often show a traceback.
Logic errors are hardest to find because there is no error message – you must test and trace the code.

Syntax errors stop the program running, logic errors run but give the wrong result, runtime errors crash it during execution.

Testing Strategies

Normal data: typical input that the program should handle correctly.
Boundary data: values at the limits of the valid range, e.g., 0, maximum, or minimum – these often reveal bugs.
Erroneous data: invalid or unexpected input, e.g., letters when numbers are expected – the program should handle gracefully.
Test with a range of inputs to ensure the program works in all cases.
Use test plans to list inputs, expected outputs, and actual outputs.

Normal, boundary and invalid test data check that a program handles each kind of input correctly.

Reading Error Messages

Error messages often include the line number and a description of the problem.
For syntax errors, look at the indicated line and the line before – the error may be there.
Runtime error messages (e.g., in Python) show a traceback with the sequence of function calls.
Read the error type (e.g., NameError, TypeError) – it tells you what kind of problem occurred.
Don't panic – read carefully and use the message to guide your search.

Debugging Techniques

Print statements: add temporary output to show variable values at different points.
Trace tables: manually step through the code, recording variable values in a table.
Breakpoints: set in a debugger to pause execution at a specific line, then inspect variables.
Step through code line by line using a debugger to see how values change.
Rubber duck debugging: explain your code line by line to a rubber duck (or a friend) – often you spot the mistake yourself.
Isolate the problem: narrow down the part of the code that causes the bug.

Breakpoints pause execution, variable inspection shows the current state, and stepping runs one instruction at a time.

Using Debuggers

A debugger is a tool that lets you monitor program execution, stop it, restart it, set breakpoints, and change values in memory.
Debuggers allow you to inspect variables at any point.
They help you step through code line by line.
High-level languages (like Python, Java) often have built-in debuggers or easy-to-use ones.
Debuggers are especially useful for finding logic errors.

A debugger runs to a breakpoint, lets you inspect the variables, then steps on to the next line.

Common Pitfalls

Off-by-one errors: loops that run one too many or too few times.
Uninitialized variables: using a variable before giving it a value.
Incorrect conditions: using = instead of ==, or wrong comparison operators.
Assuming input is always valid – always validate user input.
Not testing boundary values – these often cause failures.

Plan the test, observe the result, locate the issue, correct it, then run the test again.

Good Debugging Practice

Be systematic: test one thing at a time, change one thing at a time.
Keep a record of what you tried and what happened.
Don't guess – use evidence from tests and error messages.
Take breaks – a fresh look often helps.
Ask for help after trying reasonable steps yourself.
Learn from bugs – they help you understand your code better.

Slide

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

DAFTAR — GRATIS MASUK

Soal latihan

Pratinjau gratis — 8 dari 59 soal. Daftar untuk melihat semuanya.

1.Which term is used to describe a defect or fault in a computer program?
Easy
- ABug
- BPatch
- CDebug
- DGlitch
2.Which type of error is a violation of the rules of the programming language, such as a missing semicolon or misspelled keyword?
Easy
- ASyntax error
- BRuntime error
- CLogic error
- DType error
3.A debugger is a software tool that allows a programmer to monitor the execution of a program, set breakpoints, and change values in memory.
Easy
True or false?
4.A program asks the user to enter their age. Which of the following test inputs would be a boundary value?
Medium
- A0
- B17
- C18
- D150
5.Which of the following are common types of program errors? (select all that apply)
Medium
- ASyntax errors
- BRuntime errors
- CLogic errors
- DCompilation errors
- EDesign errors
6.Match each type of error with its description.
Medium
- Syntax error
- Runtime error
- Logic error
- Violates language rules
- Occurs during execution
- Program runs but gives wrong output
7.Put these steps of debugging a program in the correct order.
Medium
- Identify the error message
- Locate the faulty line of code
- Fix the code
- Test the program again
8.A logic error will always cause the program to crash or stop running.
Easy
True or false?

Soal lainnya

9.Match each type of program error with its correct description.
Easy
- Syntax error
- Runtime error
- Logic error
- Violates the rules of the programming language
- Occurs while the program is running, causing it to stop
- Produces wrong results because the code does not do what was intended
10.Put these steps for testing a program in the correct order.
Medium
- Test with normal data
- Test with boundary data
- Test with erroneous data
11.Which of the following are effective debugging strategies? (select all that apply)
Medium
- AReading error messages carefully
- BAdding print statements to trace values
- CIgnoring the problem and hoping it goes away
- DUsing a debugger to set breakpoints
- EAsking a friend to look at the code
12.A program is supposed to calculate the average of three numbers. It outputs 5 when the input is 2, 3, and 4. What type of error is most likely?
Medium
- ASyntax error
- BRuntime error
- CLogic error
- DCompilation error
13.Which of the following are examples of erroneous data? (select all that apply)
Medium
- AEntering a negative number for age
- BEntering a string when a number is expected
- CEntering a value outside the valid range
- DEntering a typical valid value like 25
14.Match each debugging tool or technique with its purpose.
Medium
- Breakpoint
- Print statement
- Trace table
- Pauses the program at a specific line
- Outputs values to the console
- Records the values of variables step by step
15.Arrange these debugging steps in the correct sequence.
Medium
- Reproduce the bug
- Identify the cause
- Fix the code
- Retest the program
16.A program calculates the area of a rectangle using the formula: area = length×width. When the user enters length = 5 and width = 3, the program outputs 16. What type of error is this?
Medium
- ASyntax error
- BRuntime error
- CLogic error
- DCompilation error
17.A program asks the user to enter a password that must be between 6 and 12 characters long. Which of the following test inputs are boundary values? (select all that apply)
Medium
- A5 characters
- B6 characters
- C7 characters
- D12 characters
- E13 characters
18.A program that reads a file and crashes because the file does not exist is suffering from a runtime error.
Easy
True or false?
19.Match each type of test data with its description.
Medium
- Normal data
- Boundary data
- Erroneous data
- Data that is valid and typical
- Data at the limits of valid input
- Data that is invalid or unexpected
20.Put the following steps for debugging a program in the correct order.
Medium
- Run the program with test data and observe the output
- Identify the error message or unexpected behaviour
- Trace through the code to locate the fault
- Fix the fault and re-test
21.A program is supposed to calculate the total cost of items in a shopping basket. The code is: total = 0; for each item: total = total + price. If the program outputs a total that is lower than expected, which of the following could be the cause?
Medium
- AA syntax error in the loop
- BA logic error where the total is reset to zero inside the loop
- CA runtime error from dividing by zero
- DThe program is using the wrong data type for the total
22.A program that compiles successfully can still have runtime errors.
Medium
True or false?
23.A programmer is using a debugger to find a logic error. Which of the following actions is the debugger NOT typically able to perform?
Medium
- ASet a breakpoint to pause the program at a specific line
- BChange the value of a variable while the program is running
- CRewrite the source code automatically to fix the error
- DStep through the code line by line to observe behaviour
24.Which of the following are legitimate debugging strategies? (select all that apply)
Medium
- AAdding print statements to trace variable values
- BUsing a memory dump to inspect the state of memory at a crash
- CDeleting all the code and rewriting from scratch without analysis
- DPerforming a code walk-through with another programmer
- EIgnoring error messages and guessing the cause
25.A static code analysis tool can detect a logic error that only occurs when the program is run with specific input data.
Easy
True or false?
26.A programmer is using a static analysis tool on a large codebase. A variable is used before it is assigned a value. What type of problem is this?
Medium
- ASyntax error
- BRuntime error
- CLogic error
- DSemantic error
27.The term 'bug' in the sense of a defect dates back to at least which year, when Thomas Edison used it?
Easy
- A1878
- B1945
- C1952
- D1963
28.The term 'debugging' was used in aeronautics before it entered the world of computers.
Easy
True or false?
29.According to the source, which programming language makes debugging easier because it has exception handling and type checking?
Easy
- AC
- BAssembly
- CJava
- DPython
30.In programming languages such as C or assembly, bugs may cause silent problems such as memory corruption.
Easy
True or false?
31.Which of the following is a typical example of a problem detected by static code analysis tools?
Easy
- AA missing semicolon
- BA variable dereference before assignment
- CA runtime crash due to invalid input
- DAn infinite loop
32.Static code analysis tools concentrate more on syntax than on semantics.
Easy
True or false?
33.What is the term used in the source for a more neutral way to describe an 'error' or 'defect'?
Easy
- AAnomaly
- BException
- CFault
- DMistake
34.According to the source, why might it be important to avoid a 'zero-defects' mandate?
Medium
- ABecause it is impossible to achieve zero defects
- BBecause people might deny problems to appear perfect
- CBecause it increases the cost of debugging
- DBecause it makes testing unnecessary
35.Match each type of program error with its correct example.
Easy
- Syntax error
- Runtime error
- Logic error
- Missing semicolon at the end of a statement
- Trying to divide by zero
- Using the wrong formula to calculate an average
36.Arrange the following steps for testing a program with different data types in the correct order.
Medium
- Test with normal data
- Test with boundary data
- Test with erroneous data
37.Which of the following are valid reasons for using a debugger? (select all that apply)
Medium
- ATo set breakpoints and pause execution
- BTo automatically fix all logic errors
- CTo monitor the values of variables
- DTo change values in memory during execution
- ETo replace the need for testing with normal data
38.A program is written to calculate the total cost of a shopping basket. The code is: total = 0; for each item: total = total + price. When the program is run with prices 2.50, 3.75, and 1.20, it outputs 7.45. What type of error is most likely if the program outputs 7.45 for these inputs?
Medium
- ASyntax error
- BRuntime error
- CLogic error
- DNo error
39.Which of the following are examples of erroneous data that should be used when testing a program? (select all that apply)
Medium
- AA negative number where a positive number is expected
- BA value that is exactly at the lower boundary of the valid range
- CA string of text where a number is expected
- DA value that is exactly at the upper boundary of the valid range
- EA very large number that might cause overflow
40.A program is designed to calculate the total cost of items in a shopping basket. The code uses a loop that adds the price of each item to a running total. During testing, the program gives the correct total for a basket with 3 items but gives a total that is too high for a basket with 4 items. Which type of error is most likely present?
Medium
- ASyntax error
- BRuntime error
- CLogic error
- DCompilation error
41.What is the name of the process of finding and fixing faults in a program?
Medium
42.Complete the sentence:
Easy
A ____ error occurs when a program tries to perform an illegal operation, such as dividing by zero.
43.A program should accept a temperature between -10 and 40° Celsius. How many boundary values should be tested?
Medium
44.What is the term used to describe a defect or fault in a computer program?
Easy
45.Complete the sentence about testing data.
Medium
When testing a program, data that lies on the edge of the valid input range is called ____ data.
46.A program is supposed to calculate the average of three numbers. It outputs 5 when the input is 2, 3, and 4. What is the difference between the expected output and the actual output?
Medium
47.Complete the sentence.
Easy
A ____ error occurs when a program tries to do something it is not allowed to do, such as dividing by zero.
48.A program has a line of code that says: print('Hello World') but the program does not run and reports a syntax error. What is the most likely cause?
Medium
49.Complete the sentence about the origin of the term 'bug'.
Easy
The term 'bug' in the sense of a defect dates back to at least ____ when Thomas Edison used it to describe 'little faults and difficulties' in his inventions.
50.What is the name of the software tool that enables a programmer to monitor the execution of a program, stop it, restart it, set breakpoints, and change values in memory?
Easy
51.Complete the sentence about types of errors.
Easy
A violation of the rules of the programming language, such as a missing semicolon, is called a ____ error.
52.Complete the sentence about runtime errors.
Medium
An error that occurs while a program is running, such as trying to divide by zero, is called a ____ error.
53.Explain why testing a program with erroneous data is important.
Hard
54.Explain why it is important to test a program with both boundary and erroneous data, not just normal data.
Hard
55.Explain why testing a program with boundary data is important, giving an example.
Hard
56.Explain why it is important to test a program with both normal and erroneous data, not just normal data.
Hard
57.A program written in C might cause a silent memory corruption that is hard to find, while a similar program in Java might be easier to debug. Explain why, using the reference material.
Hard
58.A program should accept a temperature between -10 and 40° Celsius. How many boundary values should be tested?
Medium
- A4
- B2
- C1
- D3
59.A program is supposed to calculate the average of three numbers. It outputs 5 when the input is 2, 3, and 4. What is the difference between the expected output and the actual output?
Medium
- A1
- B3
- C4
- D2

Catatan ulasan

## Testing and Debugging Programs ### Types of Errors - **Syntax errors**: Mistakes in the grammar of the programming language. The program won't run until these are fixed. - **Runtime errors**: Occur while the program is running, e.g., dividing by zero or trying to open a file that doesn't exist. These often crash the program. - **Logic errors**: The program runs but does the wrong thing because the logic is flawed. These are hardest to find. ### Testing with Different Data - **Normal data**: Typical inputs the program is designed to handle. - **Boundary data**: Values at the edges of the valid range (e.g., minimum and maximum). These often reveal errors. - **Erroneous data**: Invalid inputs (e.g., wrong type or out of range). A good program should handle these gracefully, not crash. ### Debugging Strategies - **Read error messages**: They often tell you the line number and type of error. - **Trace the program**: Go through your code line by line, checking values of variables. - **Use a debugger**: A tool that lets you pause execution, set breakpoints, and inspect variables. - **Add print statements**: Temporarily output values to see what's happening. - **Simplify**: Isolate the problem by testing small parts of the code. ### The Origin of "Bug" and "Debugging" - The term "bug" for a defect dates back to at least 1878, used by Thomas Edison. - A famous story: In the 1940s, Admiral Grace Hopper's team found a moth stuck in a relay of the Mark II computer, logging "First actual case of a bug being found." - "Debugging" was used in aeronautics before computing, e.g., in a 1944 letter by J. Robert Oppenheimer. ### Key Points - Not all bugs are critical; assess impact before fixing. - High-level languages (like Python or Java) often make debugging easier due to features like exception handling. - Static analysis tools can find potential errors without running the program, but may give false positives. ### Remember - Test with a range of data: normal, boundary, and erroneous. - Use systematic debugging: understand the error, trace the logic, and fix the root cause.

Syntax error: An error in the grammar of a programming language; the program cannot run until it is corrected.
Runtime error: An error that occurs while a program is running, often causing it to crash.
Logic error: An error where the program runs but produces incorrect results due to flawed logic.
Normal data: Typical inputs that a program is designed to handle correctly.
Boundary data: Inputs at the edges of the valid range, such as minimum or maximum values, often used to test edge cases.
Erroneous data: Invalid inputs that a program should handle gracefully without crashing.
Debugging: The process of finding and fixing bugs (errors) in a program.
Debugger: A software tool that helps monitor program execution, set breakpoints, and inspect variables.
Breakpoint: A point in a program where execution pauses, allowing the programmer to inspect the state.
Trace: To step through code line by line, observing the flow and variable values.
Static analysis: Analyzing source code without running it to find potential errors.
Bug: A defect or error in a program that causes incorrect behavior.

Kartu flash

What are the three main types of programming errors?

Syntax errors, runtime errors, and logic errors.

Define a syntax error.

A syntax error is a mistake in the code's grammar or structure, such as a missing semicolon or misspelled keyword, which prevents the program from running.

Define a runtime error.

A runtime error occurs while the program is running, such as division by zero or trying to access a file that doesn't exist, causing the program to crash or halt.

Define a logic error.

A logic error is a mistake in the program's algorithm or reasoning, causing it to produce incorrect results without crashing.

Why is reading error messages important?

Error messages provide clues about the type and location of a problem, helping programmers identify and fix errors more efficiently.

What is normal data in testing?

Normal data is typical, valid input that the program is expected to handle correctly.

What is boundary data in testing?

Boundary data is input at the edges of acceptable ranges, such as the minimum or maximum values, to test how the program handles limits.

What is erroneous data in testing?

Erroneous data is invalid or unexpected input that the program should handle gracefully, such as rejecting it with an error message.

What is tracing in debugging?

Tracing involves stepping through code line by line or adding print statements to track the program's execution and variable values to find where things go wrong.

What is a debugger?

A debugger is a software tool that allows programmers to monitor program execution, set breakpoints, stop and restart the program, and inspect or change memory values.

What is a breakpoint?

A breakpoint is a marker set in a debugger that pauses program execution at a specific line so the programmer can inspect the state.

What is the origin of the term 'bug' in computing?

The term 'bug' was popularized by Grace Hopper when a moth was found in a relay of the Mark II computer, though the term was used earlier by Edison.

What is the difference between a syntax error and a logic error?

A syntax error prevents the program from running due to incorrect grammar, while a logic error allows the program to run but produces wrong results.

Why might a programmer use static code analysis tools?

Static code analysis tools scan source code for known problems without running it, helping to detect issues like using a variable before it is assigned.

What is a false positive in static code analysis?

A false positive is when the tool flags correct code as potentially erroneous, which can be misleading.

What is the purpose of testing with boundary data?

Boundary testing checks how the program handles values at the edges of input ranges, which often reveal off-by-one or overflow errors.

What is the purpose of testing with erroneous data?

Erroneous data testing ensures the program handles invalid input gracefully, such as showing an error message rather than crashing.

What is the first step in debugging?

The first step is to reproduce the problem consistently so you can observe the error and begin investigating its cause.

What does 'tracing' mean in the context of debugging?

Tracing means following the flow of execution and tracking variable values to pinpoint where the program deviates from expected behavior.

What is a runtime error example?

A runtime error example is dividing by zero, which causes the program to crash during execution.

What is a logic error example?

A logic error example is using the wrong formula to calculate area, so the program runs but gives incorrect results.

Why is it important to test with a variety of data?

Testing with normal, boundary, and erroneous data helps uncover different types of errors and ensures the program is robust.

What is the role of error messages in debugging?

Error messages provide specific information about the error type and location, guiding the programmer to the source of the problem.

What is the difference between a debugger and a static analysis tool?

A debugger runs the program and allows interactive inspection, while a static analysis tool examines the code without executing it.

Unlock all 59 questions, flashcards & more

Buat akun gratis untuk melihat setiap soal, slide, kartu flash, dan catatan ulasan topik ini.

DAFTAR — GRATIS MASUK

Soal ujian lampau

Latihan soal ujian lampau untuk topik ini segera hadir.

Segera hadir