Debugging MCQ Questions in C

Debugging is an essential skill for every programmer, and the C programming language is no exception. In this article, we will delve into the realm of C debugging, addressing frequent concerns and debugging questions in C. From learning the fundamentals of debugging to confronting complex problems, we have you covered. Therefore, let’s roll up our sleeves and embark on this diagnostic expedition!

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What is Debugging in C?

Debugging is the process of locating and fixing errors or flaws within a computer program. This involves locating and correcting errors in your source code that prevent it from executing properly in C. Debugging is an essential skill for programmers, as it ensures that their code functions as intended.

Debugging Questions in C (FAQs)


1. What is debugging in C?

   a) Writing code

   b) Testing code

   c) Identifying and fixing errors in code

   d) Compiling code

Answer: c) Identifying and fixing errors in code


2. Which of the following is not a common type of error in C programming?

   a) Syntax error

   b) Runtime error

   c) Logical error

   d) Compilation error

Answer: d) Compilation error


3. What does a segmentation fault error indicate in C?

   a) Syntax error

   b) Memory access violation

   c) Infinite loop

   d) Compilation error

Answer: b) Memory access violation


4. Which tool is commonly used for debugging C programs?

   a) Visual Studio

   b) Sublime Text

   c) Notepad

   d) Microsoft Word

   Correct Answer: a) Visual Studio

Answer: a) Visual Studio


5. What is the purpose of a breakpoint in a debugger?

   a) To end the program

   b) To print a message

   c) To pause program execution at a specific point

   d) To compile the code

Answer: c) To pause program execution at a specific point


6. Which debugging technique involves adding print statements to the code to trace its execution?

   a) Code analysis

   b) Code profiling

   c) Code walkthrough

   d) Print debugging

Answer: d) Print debugging


7. Which command-line option is often used to enable debugging information when compiling with GCC?

   a) -O0

   b) -g

   c) -DDEBUG

   d) -Wall

Answer: b) -g


8. When debugging a program, what does “stepping into” a function mean?

   a) Skipping the function

   b) Exiting the program

   c) Going deeper into the function’s code

   d) Jumping to a random location

Answer: c) Going deeper into the function’s code


9. What does the “core dump” file contain in C debugging?

   a) The source code

   b) Compiler errors

   c) Debugging information

   d) Information about a program’s crash

Answer: d) Information about a program’s crash


10. Which type of error is often detected by a static code analyzer?

    a) Syntax error

    b) Runtime error

    c) Logical error

    d) Compilation error

Answer: d) Information about a program’s crash


11. What is a “watchpoint” in debugging?

    a) A tool to measure CPU usage

    b) A variable used for counting

    c) A point in the code where the debugger stops execution

    d) A mechanism to break when a specific variable’s value changes

Answer: d) A mechanism to break when a specific variable’s value changes


12. What is the purpose of the “core dump” file in C debugging?

    a) To store backup copies of source code

    b) To create a snapshot of the program’s memory at the time of a crash

    c) To log debugging messages

    d) To store temporary data during debugging

Answer: b) To create a snapshot of the program’s memory at the time of a crash


13. Which of the following is not a commonly used debugging technique in C?

    a) Breakpoint debugging

    b) Step-through debugging

    c) Code profiling

    d) Code walkthrough

Answer: c) Code profiling


14. What is a “stack overflow” error in C?

    a) An error caused by excessive function calls

    b) An error in the memory allocation functions

    c) An error in the compiler

    d) An error related to file I/O operations

Answer: a) An error caused by excessive function calls


15. What is a “memory leak” in C programming?

    a) A situation where the program runs out of memory

    b) A situation where memory is allocated but never deallocated

    c) A situation where the program crashes due to insufficient memory

    d) A situation where memory is deallocated but never allocated

Answer: b) A situation where memory is allocated but never deallocated


16. In C debugging, what does the term “core” refer to?

    a) A part of the CPU

    b) A data structure

    c) A file containing debugging information

    d) A file containing a memory dump of a crashed program

Answer: d) A file containing a memory dump of a crashed program


17. Which debugging technique involves running a program with known input and comparing the output to the expected result?

    a) Print debugging

    b) Black-box testing

    c) Code profiling

    d) Code walkthrough

Answer: b) Black-box testing


18. What does the “assert” macro in C help with?

    a) Printing debugging information

    b) Terminating the program

    c) Checking if a condition is true and terminating the program if it’s false

    d) Compiling the code

Answer: c) Checking if a condition is true and terminating the program if it’s false


19. What is a “race condition” in C programming?

    a) A situation where multiple threads access shared resources concurrently, leading to unexpected behavior

    b) A situation where the program uses excessive memory

    c) A situation where a program enters an infinite loop

    d) A situation where the program crashes due to a missing header file

Answer: a) A situation where multiple threads access shared resources concurrently, leading to unexpected behavior


20. Which of the following debugging tools allows you to inspect the call stack?

    a) GDB (GNU Debugger)

    b) GCC (GNU Compiler Collection)

    c) Makefile

    d) Valgrind

Answer: a) GDB (GNU Debugger)


21. What is “dynamic memory allocation” in C?

    a) Allocating memory at compile-time

    b) Allocating memory at runtime using functions like malloc and free

    c) Allocating memory for global variables

    d) Allocating memory using the “new” keyword

Answer: b) Allocating memory at runtime using functions like malloc and free


22. In C debugging, what does the “call stack” represent?

    a) A list of function calls made by the program

    b) A list of compiler errors

    c) A list of debugging commands

    d) A list of program variables

Answer: a) A list of function calls made by the program


23. What is a “core dump analysis”?

    a) Analyzing the program’s source code

    b) Analyzing the program’s output

    c) Analyzing the memory dump of a crashed program

    d) Analyzing the program’s execution time

Answer: c) Analyzing the memory dump of a crashed program


24. Which of the following is NOT a common debugging tool or utility in C?

    a) Valgrind

    b) GDB

    c) printf

    d) strace

Answer: c) printf


25. What is the purpose of the “volatile” keyword in C?

    a) To declare a variable as constant

    b) To declare a variable as non-modifiable

    c) To indicate that a variable’s value can change unexpectedly (e.g., by hardware)

    d) To specify the type of a variable

Answer: c) To indicate that a variable’s value can change unexpectedly (e.g., by hardware)


26. Which of the following is NOT a typical source of runtime errors in C?

    a) Division by zero

    b) Uninitialized variables

    c) Incorrect syntax

    d) Buffer overflows

Answer: c) Incorrect syntax


27. What is “static analysis” in C debugging?

    a) Analyzing the program’s execution time

    b) Analyzing the program’s source code without executing it

    c) Analyzing the program’s output

    d) Analyzing the program’s memory usage

Answer: b) Analyzing the program’s source code without executing it


28. What does “step over” mean in a debugger?

    a) Skip the current line of code

    b) Terminate the program

    c) Move to the next line of code, skipping function calls

    d) Restart the program

Answer: c) Move to the next line of code, skipping function calls


29. What is the purpose of the “break” statement in C?

    a) To exit a loop or switch statement

    b) To create a breakpoint for debugging

    c) To terminate the program

    d) To define a function

Answer: a) To exit a loop or switch statement


30. Which type of error is typically detected at compile-time?

    a) Runtime error

    b) Syntax error

    c) Logical error

    d) Memory leak

Answer: b) Syntax error


31. What is the primary use of the “errno” variable in C?

    a) To store the program’s execution time

    b) To indicate the presence of a memory leak

    c) To store error codes for system calls

    d) To measure the CPU usage of the program

Answer: c) To store error codes for system calls


32. What is “conditional compilation” in C?

    a) Compiling code only if certain conditions are met

    b) Compiling code without any conditions

    c) Compiling code using a specific compiler

    d) Compiling code conditionally based on the current date

Answer: a) Compiling code only if certain conditions are met


33. What is the purpose of the “setjmp” and “longjmp” functions in C?

    a) To set and retrieve the program’s execution time

    b) To set and retrieve breakpoints

    c) To perform arithmetic operations

    d) To perform non-local jumps within the program

Answer: d) To perform non-local jumps within the program


34. Which of the following is NOT a common debugging strategy?

    a) Black-box testing

    b) White-box testing

    c) Glass-box testing

    d) Gray-box testing

Answer: a) Black-box testing


35. In C, what does the “const” keyword indicate?

    a) A variable that cannot be modified after declaration

    b) A variable that can be modified freely

    c) A function that performs constant calculations

    d) A function that cannot return a value

Answer: a) A variable that cannot be modified after declaration


36. What does the “SIGSEGV” signal indicate in C?

    a) Successful program execution

    b) Division by zero

    c) Segmentation fault (memory access violation)

    d) Syntax error

Answer: c) Segmentation fault (memory access violation)


37. In C, what does the “assert” function do?

    a) Print debugging information

    b) Terminate the program

    c) Check a condition and terminate the program if it’s false

    d) Print compiler errors

Answer: c) Check a condition and terminate the program if it’s false


38. What is the primary goal of code review in debugging?

    a) To identify and fix errors in code

    b) To test the code

    c) To write new code

    d) To compile the code

Answer: a) To identify and fix errors in code


39. What is “unit testing” in the context of debugging?

    a) Testing individual functions or modules in isolation

    b) Testing the entire program as a whole

    c) Testing the user interface of the program

    d) Testing the program with a large dataset

Answer: a) Testing individual functions or modules in isolation


40. What does the “malloc” function in C do?

    a) Terminate the program

    b) Allocate memory for a new process

    c) Allocate dynamic memory on the heap

    d) Allocate memory on the stack

Answer: c) Allocate dynamic memory on the heap


41. In C debugging, what is the purpose of the “core dump” file?

    a) To store a copy of the source code

    b) To store debugging messages

    c) To create a snapshot of the program’s memory at the time of a crash

    d) To store temporary data during debugging

Answer: c) To create a snapshot of the program’s memory at the time of a crash


42. What does “stack smashing” refer to in C programming?

    a) A technique used to optimize stack memory usage

    b) A technique used to reduce CPU usage

    c) A type of buffer overflow vulnerability that corrupts the stack

    d) A type of segmentation fault error

Answer: c) A type of buffer overflow vulnerability that corrupts the stack


43. Which of the following is a common practice in C debugging?

    a) Ignoring compiler warnings

    b) Using descriptive variable names

    c) Avoiding comments in code

    d) Writing lengthy functions

Answer: b) Using descriptive variable names


44. What is a “core dump analysis”?

    a) Analyzing the program’s source code

    b) Analyzing the program’s output

    c) Analyzing the memory dump of a crashed program

    d) Analyzing the program’s execution time

Answer: c) Analyzing the memory dump of a crashed program


45. In C programming, what is the purpose of the “volatile” keyword?

    a) To declare a variable as constant

    b) To declare a variable as non-modifiable

    c) To indicate that a variable’s value can change unexpectedly (e.g., by hardware)

    d) To specify the type of a variable

Answer: c) To indicate that a variable’s value can change unexpectedly (e.g., by hardware)


46. Which of the following is NOT a common debugging tool or utility in C?

    a) Valgrind

    b) GDB

    c) printf

    d) strace

Answer: c) printf


47. What is the primary use of the “errno” variable in C?

    a) To store the program’s execution time

    b) To indicate the presence of a memory leak

    c) To store error codes for system calls

    d) To measure the CPU usage of the program

Answer: c) To store error codes for system calls


48. What is “conditional compilation” in C?

    a) Compiling code only if certain conditions are met

    b) Compiling code without any conditions

    c) Compiling code using a specific compiler

    d) Compiling code conditionally based on the current date

Answer: a) Compiling code only if certain conditions are met


49. What is the purpose of the “setjmp” and “longjmp” functions in C?

    a) To set and retrieve the program’s execution time

    b) To set and retrieve breakpoints

    c) To perform arithmetic operations

    d) To perform non-local jumps within the program

Answer: d) To perform non-local jumps within the program


50. Which of the following is NOT a typical source of runtime errors in C?

    a) Division by zero

    b) Uninitialized variables

    c) Incorrect syntax

    d) Buffer overflows

Answer: c) Incorrect syntax


Conclusion

Debugging in C is a necessary skill for all programmers. You can become a more proficient C programmer by comprehending the debugging procedure, utilizing the appropriate tools, and addressing prevalent queries and issues. Remember that debugging is a journey of problem-solving that frequently results in improved code quality and a deeper comprehension of the language.

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