Advanced C Programming MCQs Questions and Answers
C Programming is one of the most widely-used programming languages initially developed by Dennis Ritchie. It is a general and imperative programming language, which is much faster than programming languages like Java and Python.
C Programming is known for its efficiency and low-level manipulation capabilities, making it a preferred choice for system-level programming and embedded systems. It is extensively used in various technologies and applications, ranging from operating systems, firmware development, and game development to microcontroller programming.
If you aspire to excel in C Programming, it’s essential to not only understand the basics but also delve into advanced concepts to tackle challenges posed in various domains.
As you prepare for your journey in C Programming, consider familiarizing yourself with c programming viva questions, switch case in c programming questions, c programming mcq questions, c programming basic questions, and c programming aptitude questions.
This diverse set of questions covers fundamental concepts, decision-making structures like switch case, multiple-choice questions, basic programming queries, and aptitude assessments, providing a holistic approach to mastering the language.
Other than that is a very flexible programming language, as it can be used in technologies and applications. Due to its high performing nature, it is often used in companies like Microsoft, Opera, NASA, Meta and LinkedIn.
If you dream of working in these famous companies, you need to be an expert in this programming language. These MCQs will help you in getting a better understanding of this programming language, as they are based on error finding, C algorithms, code outputs, and C coding questions.
Q1. What is the purpose of the `volatile` keyword in C programming?
- It indicates that a variable’s value may change at any time without any action being taken by the code.
- It specifies that a variable cannot be modified.
- It forces the compiler to optimize the variable aggressively.
- It is used to define constant values.
Answer: A
Explanation: The `volatile` keyword is used to indicate that a variable’s value can be changed at any time by external factors (e.g., hardware), and the compiler should not perform aggressive optimizations on it.
Q 2. Which of the following data types in C has the highest storage size?
- char
- int
- long
- double
Answer: D
Explanation: Among the given options, the `double` data type typically has the highest storage size because it is used to represent double-precision floating-point numbers.
Q3. What is the purpose of the `typedef` keyword in C?
- It is used to create a new data type.
- It is used to declare a variable.
- It is used to define a function.
- It is used to include header files.
Answer: A
Explanation: The `typedef` keyword is used to create new data types in C, making code more readable and maintainable.
Q 4. In C, what is the purpose of the `#include` directive?
- It is used to declare a function.
- It is used to define a macro.
- It is used to include a header file in the program.
- It is used to declare a structure.
Answer: C
Explanation: The `#include` directive is used to include header files in a C program, allowing you to use functions and declarations from those header files.
Q 5. What is the scope of a global variable in C?
- It is limited to the function in which it is declared.
- It is limited to the block in which it is declared.
- It is limited to the file in which it is declared.
- It is limited to the program in which it is declared.
Answer: D
Explanation: Global variables in C have a scope that extends throughout the entire program in which they are declared.
Q 6. What is the purpose of the `malloc` function in C?
- It is used to declare a new variable.
- It is used to allocate memory dynamically.
- It is used to create a new file.
- It is used to print output to the console.
Answer: B
Explanation: The `malloc` function in C is used to allocate memory dynamically at runtime.
Q 7. Which operator is used to access the members of a structure in C?
- . (dot)
- -> (arrow)
- , (comma)
- :: (scope resolution)
Answer: A
Explanation: The dot (.) operator is used to access the members of a structure in C.
Q 8. What is the result of bitwise XOR (^) operation between 5 and 3 in C?
- 0
- 1
- 2
- 8
Answer: A
Explanation: The bitwise XOR operation between 5 (binary 101) and 3 (binary 011) results in 6 (binary 110), which is 0 in decimal.
Q 9. In C, what is the purpose of the `break` statement in a `switch` statement?
- It terminates the program.
- It exits the current loop.
- It transfers control to a specific case label.
- It continues to the next case label.
Answer: B
Explanation: The `break` statement in a `switch` statement is used to exit the current loop and continue with the code after the `switch` block.
Q 10. What is the output of the following code snippet?
“`c
#include <stdio.h>
int main() {
int x = 5;
int y = ++x + x++;
printf(“%d”, y);
return 0;
}
“`
- 10
- 11
- 12
- 13
Answer: B
Explanation: The expression `++x` increments `x` to 6 and returns 6, and `x++` returns the current value of `x` (6) and then increments `x` to 7. So, `y` is calculated as 6 + 6 = 12.
Q 11. What does the `sizeof` operator in C return?
- The size of a variable in bytes.
- The value of a variable.
- The address of a variable.
- The type of a variable.
Answer: A
Explanation: The `sizeof` operator in C returns the size of a variable or data type in bytes.
Q 12. In C, which function is used to close a file?
- close()
- fclose()
- file_close()
- endfile()
Answer: B
Explanation: The `fclose()` function is used to close a file in C.
Q 13. What is the purpose of the `static` keyword when applied to a local variable in C?
- It makes the variable global.
- It allocates memory on the heap.
- It preserves the variable’s value between function calls.
- It initializes the variable to zero.
Answer: C
Explanation: When `static` is applied to a local variable, it preserves the variable’s value between function calls.
Q 14. Which of the following functions is used to compare two strings in C?
- compare()
- strcmp()
- strcompare()
- strcasecmp()
Answer: B
Explanation: The `strcmp()` function is used to compare two strings in C. It returns 0 if the strings are equal.
Q 15. What is the purpose of the `const` keyword in C?
- It makes a variable constant and unchangeable.
- It specifies a variable as an integer.
- It is used to declare a constant value.
- It creates a constant function.
Answer: A
Explanation: The `const` keyword is used to make a variable constant and unchangeable in C.
Q 16. Which header file is needed to use dynamic memory allocation functions like `malloc` and `free` in C?
- <stdlib.h>
- <memory.h>
- <malloc.h>
- <stdio.h>
Answer: A
Explanation: The <stdlib.h> header file is required to use dynamic memory allocation functions like `malloc` and `free` in C.
Q 17. In C, which operator is used for logical AND?
- &&
- &
- and
- AND
Answer: A
Explanation: The `&&` operator is used for logical AND in C.
Q 18. What does the `#ifdef` preprocessor directive check for in C?
- It checks if a variable is defined.
- It checks if a variable is undefined.
- It checks if a function is defined.
- It checks if a variable is negative.
Answer: A
Explanation: The `#ifdef` preprocessor directive checks if a variable is defined.
Q 19. What is the purpose of the `register` keyword in C?
- It specifies a variable as a pointer.
- It allocates memory on the stack.
- It is used to define a register in the CPU.
- It suggests that a variable should be stored in a CPU register.
Answer: D
Explanation: The `register` keyword suggests that a variable should be stored in a CPU register for faster access.
Q 20. What is the primary use of a function prototype in C?
- It defines the function’s behavior.
- It declares a function before its actual definition.
- It specifies the return type of a function.
- It indicates that a function is recursive.
Answer: B
Explanation: A function prototype in C is used to declare a function before its actual definition, providing the compiler with information about the function’s signature.
Q 21. What is the purpose of the `#pragma` directive in C?
- It is used to define macros.
- It is used for conditional compilation.
- It is used for compiler-specific instructions.
- It is used for loop control.
Answer: C
Explanation: The `#pragma` directive is used for compiler-specific instructions and extensions.
Q 22. Which of the following standard C library functions is used for memory allocation and deallocation?
- malloc()
- printf()
- strcpy()
- sin()
Answer: A
Explanation: The `malloc()` function is used for dynamic memory allocation in C.
Q 23. What does the `volatile` keyword indicate when applied to a pointer in C?
- The pointer can’t be modified.
- The pointer is volatile, and its address can change.
- The pointer points to constant data.
- The pointer is used for I/O operations.
Answer: B
Explanation: When the `volatile` keyword is applied to a pointer, it indicates that the pointer is volatile, and its address can change.
Q 24. Which function is used to read a character from the standard input in C?
- getc()
- read()
- getchar()
- scan()
Answer: C
Explanation: The `getchar()` function is used to read a character from the standard input in C.
Q 25. In C, what is the result of `sizeof(char)`?
- 1
- 2
- 4
- Depends on the system
Answer: A
Explanation: The `sizeof(char)` is always 1 in C, regardless of the system.
Q 26. What is the purpose of the `inline` keyword in C?
- It specifies a function to be called indirectly.
- It is used for macro substitution.
- It indicates that a function should be inlined by the compiler.
- It declares a variable that can be changed by the program.
Answer: C
Explanation: The `inline` keyword is used to indicate that a function should be inlined by the compiler for performance optimization.
Q 27. In C, what does the `<<` operator represent in the context of bitwise operations?
- Logical OR
- Logical AND
- Bitwise left shift
- Bitwise right shift
Answer: C
Explanation: The `<<` operator represents a bitwise left shift operation in C.
Q 28. What is the purpose of the `restrict` keyword in C?
- It restricts the use of the `goto` statement.
- It restricts the use of memory allocation functions.
- It indicates that a pointer is the only reference to the pointed-to memory.
- It restricts the use of inline functions.
Answer: C
Explanation: The `restrict` keyword indicates that a pointer is the only reference to the pointed-to memory, allowing the compiler to optimize better.
Q 29. Which standard C library function is used to compare two blocks of memory in C?
- memcmp()
- memcomp()
- memcompare()
- comparemem()
Answer: A
Explanation: The `memcmp()` function is used to compare two blocks of memory in C.
Q 30. What is the output of the following code snippet?
“`c
#include <stdio.h>
int main() {
char str[] = “Hello, World!”;
printf(“%s”, str + 7);
return 0;
}
“`
- “Hello, World!”
- “World!”
- “World!”
- “ello, World!”
Answer: B
Explanation: The code prints the substring starting from the 7th character of the string “Hello, World!” which is “World!”.
Q 31. What does the `offsetof` macro in C provide?
- The size of a data type.
- The offset of a member within a structure.
- The size of an array.
- The offset of a variable in memory.
Answer: B
Explanation: The `offsetof` macro is used to find the offset of a member within a structure.
Q 32. Which of the following statements is true regarding `const` pointers in C?
- A `const` pointer can be used to modify the data it points to.
- A `const` pointer cannot be reassigned to point to a different location.
- A `const` pointer can only point to dynamically allocated memory.
- A `const` pointer can be dereferenced to modify the data it points to.
Answer: B
Explanation:** A `const` pointer cannot be reassigned to point to a different location. However, it can still be used to modify the data it points to.
Q 33. In C, which operator is used to access the address of a variable?
- & (ampersand)
- * (asterisk)
- @ (at)
- # (hash)
Answer: A
Explanation: The & (ampersand) operator is used to access the address of a variable in C.
Q 34. What is the output of the following code snippet?
“`c
#include <stdio.h>
int main() {
int x = 5;
int y = (x++) + (++x);
printf(“%d”, y);
return 0;
}
“`
- 9
- 10
- 11
- 12
Answer: C
Explanation: The expression `(x++) + (++x)` is evaluated as `(5++) + (++6)` which results in `5 + 7 = 12`.
Q 35. What is the purpose of the `union` data type in C?
- It is used to declare arrays.
- It is used to group together variables of different data types.
- It is used to create linked lists.
- It is used to define constant values.
Answer: B
Explanation: A `union` in C is used to group together variables of different data types, but only one of them can be used at a time.
Q 36. Which library should be included to use the `sqrt` function for calculating the square root in C?
- <math.h>
- <cmath.h>
- <stdio.h>
- <stdlib.h>
Answer: A
Explanation: The `sqrt` function for calculating the square root is available in the <math.h> library in C.
Q 37. What is the purpose of the `do…while` loop in C?
- It is used for iteration.
- It is used for decision-making.
- It ensures that a block of code is executed at least once.
- It is used to break out of a loop.
Answer: C
Explanation: The `do…while` loop in C ensures that a block of code is executed at least once, and then it checks the loop condition.
Q 38. Which header file is required to work with file I/O in C?
- <io.h>
- <fileio.h>
- <stdio.h>
- <inputoutput.h>
Answer: C
Explanation: The <stdio.h> header file is required to work with file I/O in C.
Q 39. In C, which operator is used for bitwise OR?
- | (pipe)
- |& (pipe-ampersand)
- |* (pipe-asterisk)
- || (logical OR)
Answer: A
Explanation: The | (pipe) operator is used for bitwise OR in C.
Q 40. What is the output of the following code snippet?
“`c
#include <stdio.h>
int main() {
int a = 10, b = 20, c;
c = a > b ? a : b;
printf(“%d”, c);
return 0;
}
“`
- 10
- 20
- 30
- Error
Answer: B
Explanation: The code uses the conditional (ternary) operator to assign the value of `a` to `c` if `a` is greater than `b`, otherwise, it assigns the value of `b` to `c`, resulting in `c` being equal to 20.
Q 41. What does the `#define` directive do in C?
- It declares a function.
- It defines a constant or macro.
- It declares a variable.
- It is used to include header files.
Answer: B
Explanation: The `#define` directive is used to define constants and macros in C.
Q 42. What is the purpose of the `int main(int argc, char* argv[])` function signature in C?
- It specifies a function to take integer arguments.
- It is the entry point of a C program that accepts command-line arguments.
- It defines a function with no arguments.
- It is used for memory allocation.
Answer: B
Explanation: The `int main(int argc, char* argv[])` function signature is used for the entry point of a C program that accepts command-line arguments.
Q 43. What is the result of `sizeof(int)` on a 32-bit system?
- 1 byte
- 2 bytes
- 4 bytes
- 8 bytes
Answer: C
Explanation: On a 32-bit system, the `sizeof(int)` is typically 4 bytes.
Q 44. In C, what is the purpose of the `continue` statement in a loop?
- It terminates the loop.
- It skips the rest of the loop’s body and proceeds to the next iteration.
- It returns a value from the loop.
- It restarts the loop from the beginning.
Answer: B
Explanation: The `continue` statement in a loop skips the rest of the loop’s body and proceeds to the next iteration.
Q 45. Which standard C library function is used for character input from a file pointer?
- fgetc()
- fgets()
- getchar()
- scanf()
Answer: A
Explanation: The `fgetc()` function is used for character input from a file pointer in C.
Q 46. In C, what is the purpose of the assert macro?
- It checks if a file exists.
- It evaluates an expression and, if it is false, triggers an assertion failure.
- It is used to define macros.
- It specifies the return type of a function.
Answer: B
Explanation: The assert macro is used to evaluate an expression, and if it is false, it triggers an assertion failure, indicating that a critical condition has not been met.
Q 47. Which operator is used for pointer arithmetic in C?
- + (plus)
- – (minus)
- * (asterisk)
- / (forward slash)
Answer: B
Explanation: The – (minus) operator is used for pointer arithmetic in C.
Q 48. What is the purpose of the strcat function in C?
- It converts a string to uppercase.
- It compares two strings.
- It concatenates two strings.
- It calculates the string length.
Answer: c
Explanation: The strcat function in C is used to concatenate two strings.
Q 49. Which standard C library function is used for converting a string to an integer?
- str2int()
- atoi()
- itoa()
- int2str()
Answer: b
Explanation: The atoi() function is used for converting a string to an integer in C.
Q 50. What is the output of the following code snippet?
c
Copy code
#include <stdio.h>
int main() {
int x = 5;
int y = x << 2;
printf(“%d”, y);
return 0;
- 5
- 10
- 15
- 20
Answer: D
Explanation: The code uses the left shift operator (<<) to shift the bits of x to the left by 2 positions, resulting in y being equal to 20.
