C Programming MCQ: From Basics To Advance!

1. What is the correct syntax to declare a variable in C?

a) int 1number;

b) int number1;

c) int number 1;

d) int number-1;

Answer: (b) int number1;

Explanation: In programming with C, variables can be defined with a data type, along with a valid name or an identifier. The variable name must start with a letter or underscore; it can also contain digits, but cannot contain spaces, nor can it begin with a digit. For instance, "int number1;" is a valid declaration of a variable because it follows these rules.

In addition, using proper syntax in a program can avoid compiler errors. Descriptors such as "1number" or "number-1" are not acceptable because they begin with a digit or contain an invalid character, respectively. Naming variables according to the rules avoids errors and helps make your code readable and maintainable.

2. Which of the following is a valid comment in C?

a) // This is a comment

b) /* This is a comment */

c) # This is a comment

d) Both a and b

Answer: (d) Both a and b

Explanation: In C programming, there are two acceptable ways to write comments. You can use the single-line comment style with "//" or the multi-line comment style with "/* ... */". Both methods allow you to add notes or explanations to your code without affecting its execution.

On the other hand, using a "#" for comments is not valid in C. This means that while options a) and b) are correct ways to comment, option c) is not allowed. Therefore, the correct answer is option d), which indicates that both single-line and multi-line comments are valid in C.

3. Which operator is used to access members of a structure in C?

a) .

b) ->

c) Both a and b

d) ::

Answer: (c) Both a and b

Explanation: You can access members of a structure using either the dot operator (.) or the arrow operator (->). The dot operator is used when you have an actual structure variable. For example, if you declare a structure variable directly, you would use the dot operator to access its members.

On the other hand, when you have a pointer to a structure, you use the arrow operator to access its members. Both operators serve the purpose of member access, but the choice depends on whether you are dealing with a structure variable or a pointer to a structure. This is why the correct answer is that both a and b are valid. This is why the correct answer is that both a and b are valid in C programming MCQ questions.

4. What will be the output of the following code?

#include <stdio.h>
int main() 
{    
int x = 5;    
printf("%d", x++);    
return 0;
}

a) 5

b) 6

c) Compilation error

d) Undefined behavior

Answer: (a) 5

Explanation: The post-increment operator (x++) evaluates the current value of the variable before increasing it. In the given code, the variable x is initially set to 5. When the printf function is executed with x++, it prints the value 5.

After printing, the value of x is incremented to 6, but this new value is not used in the output. This means that even though x is increased after the print operation, the program outputs the original value of x, which is 5. Therefore, the correct answer is (a) 5. This concept is frequently tested in C language MCQ questions.

5. Which of these data types can store decimal numbers in C?

a) int

b) float

c) char

d) double

Answer: (b and d) float and double

Explanation: Decimal numbers require a data type that can handle fractional values. The data types designed for this purpose are float and double. These types allow you to store numbers with decimal points, which is essential for calculations requiring precision.

While both float and double store decimal numbers, double offers higher precision than float. This means that double can handle more significant digits and is more accurate for computations. In contrast, int and char are not suitable for decimal values as they only represent whole numbers and characters. This concept is commonly tested in C Programming MCQ questions.

6. Which operator is used to perform a bitwise AND operation in C?

a) &
b) &&
c) |
d) ^

Answer: a) &

Explanation: The single ampersand (&) is used for bitwise AND, which compares each bit of two numbers and returns 1 only if both bits are 1.

7. Which operator is used for bitwise exclusive OR (XOR) in C?

a) ^
b) &&
c) |
d) ~

Answer: a) ^

Explanation: The caret (^) operator performs bitwise XOR, which returns 1 for each bit position where the corresponding bits of either but not both operands are 1.

Which operator in C can invert (toggle) all bits of an integer?

a) &
b) |
c) ~
d) ^

Answer: c) ~

Explanation: The tilde (~) is the bitwise NOT operator, which flips all bits of its operand.

8. Which statement is used to immediately exit the current loop in C?

a) continue
b) break
c) exit
d) return

Answer: b) break

Explanation: The break statement immediately exits the nearest enclosing loop or switch statement.

9. Which of the following is a correct syntax for a do-while loop in C?

a) do { … } while (condition);
b) while (condition) { … }
c) do (condition) { … }
d) loop { … } while (condition);

Answer: a) do { … } while (condition);

Explanation: The do-while loop executes the block at least once before checking the condition.

10. Which keyword allows you to jump to a labeled statement in C?

a) continue
b) break
c) goto
d) switch

Answer: c) goto

Explanation: The goto statement transfers control to a labeled statement within the same function.

11. What is the output of the following code?

#include <stdio.h> 
int main() 
{ 
int i = 0; 
for (;;) 
{ 
if (i == 2) 
break;
printf("%d ", i++);
} return 0; 
}

a) 0 1 2
b) 0 1
c) 1 2
d) Infinite loop

Answer: b) 0 1

Explanation: The loop prints 0 and 1, then breaks when i == 2.

12. Which function must be present in every C program for it to execute?

a) entry()
b) main()
c) start()
d) init()

Answer: b) main()

Explanation: The main() function is the entry point for execution in every C program.

13. What file extension is typically used for C header files?

a) .c
b) .h
c) .cpp
d) .exe

Answer: b) .h

Explanation: Header files in C have the .h extension.

14. Which of the following is a correct function prototype for a function that returns float and takes two int parameters?

a) float func(int, int);
b) float func(a, b);
c) func float(int, int);
d) float func(int a, int b);

Answer: a) and d) are both correct

Explanation: Both forms are valid as function prototypes.

15. Where should global variables be declared in a C program?

a) Inside any function
b) Outside all functions
c) Only in the main() function
d) Inside header files only

Answer: b) Outside all functions

Explanation: Global variables are declared outside all functions and are accessible throughout the program.

16. Which of the following is a character constant in C?

a) 'A'
b) "A"
c) A
d) 65

Answer: a) 'A'

Explanation: Character constants are enclosed in single quotes, such as 'A'.

17. Which keyword is used to declare a variable that is intended to be immutable?

a) static
b) const
c) register
d) inline

Answer: b) const

Explanation: The const keyword is used in C to define a variable whose initialized value will never change; therefore, it is permanently defined as constant or immutable.

18. Which storage class is best suited for a variable with dynamic variable values that should be visible only within a function?

a) static
b) auto
c) extern
d) const

Answer: b) auto

Explanation: auto is the default storage class for local variables whose values can change dynamically within a function.

19. Which of the following is a valid variable name in C?

a) int
b) 1var
c) my_var
d) char constant

Answer: c) my_var

Explanation: Variable names in C must start with a letter or underscore and cannot use keywords or spaces.

20. Which of the following is a character constant in C?

a) 'A'
b) "A"
c) 65
d) char

Answer: a) 'A'

Explanation: A character constant is a single character defined in between single quotes.

21. Which keyword is used to declare a variable that cannot be changed after initialization?

a) static
b) const
c) register
d) inline

Answer: b) const

Explanation: The const keyword makes a variable immutable.

22. Which storage class is used for variables that have automatic storage duration and block scope?

a) static
b) extern
c) auto
d) register

Answer: c) auto

Explanation: auto is the default storage class for local variables.

23. Which of the following is a valid variable name in C?

a) pointer
b) 1value
c) dynamic variable values
d) char constant

Answer: a) pointer

Explanation: Identifiers must start with a letter or underscore and cannot contain a space.

24. Which preprocessor directive is used to define a constant or macro in C?

a) #include
b) #define
c) #ifdef
d) #pragma

Answer: b) #define

Explanation: The #define directive is used to define constants or macros.

25. What is the purpose of the #include directive in C?

a) To include a function definition
b) To include a header file or source file
c) To define a macro
d) To start conditional compilation

Answer: b) To include a header file or source file

Explanation: #include is used for file inclusion, typically header files with a .h extension.

26. Which file extension is commonly used for C header files included using #include?

a) .exe
b) .c
c) .h
d) .cpp

Answer: c) .h

Explanation: Header files in C commonly use the .h extension.

27. Which preprocessor directive is used for conditional compilation based on whether a macro is defined?

a) #define
b) #ifdef
c) #include
d) #pragma

Answer: b) #ifdef

Explanation: #ifdef checks if a macro has been defined and allows conditional compilation.

Quick Summary: Basic C Language MCQs

This section strengthens the core fundamentals every C learner must master before moving to deeper topics. It covers variable rules, comments, structure access, increment behavior, data types, bitwise basics, control flow, function prototypes, storage classes, and preprocessor essentials. You learn how C actually interprets names, operators, and headers, why certain syntax works (or fails), and how small mistakes, like using the wrong operator or missing a header, cause errors. By the end, you build a clean, exam-ready foundation for writing correct, predictable, and safe C programs.

28. What does the size of the operator do in C?

a) Returns the size of an array

b) Returns the size of a variable type in bytes

c) Returns the total size of all variables

d) None of the above

Answer: (b) Returns the size of a variable type in bytes

Explanation: The size of the operator is used to select the size of a variable type or data structure in bytes. It helps you know how much memory a particular type occupies during program execution. This operator is useful for memory allocation and ensuring compatibility across different systems.

The size of the operator does not sum up the size of all variables or target arrays; instead, it returns the size of the specified operand in bytes. This precise functionality makes it an essential tool for writing robust, portable C programs. Thus, the correct answer is that it returns the size of a variable type in bytes.

29. What will be the output of this code snippet?

#include <stdio.h>
int main() 
{   
int x = 10;    
int y = 20;   
printf("%d", x + y);   
return 0;
}

a) 10

b) 20

c) 30

d) Compilation error

Answer: (c) 30

Explanation: Two integer variables are defined, x and y, and each of these variables is assigned a value (i.e., 'x' was assigned to 10 and 'y' was assigned to 20). Later on, the printf() function is used to print the aggregate result of the two variables. Since x + y is equal to (10 + 20), this program outputs 30.

The code is correct and will compile without any errors because the syntax is proper, and all necessary components, like #include <stdio.h> for input/output functions, are included. Therefore, when the program runs it will display 30. This is a commonly asked concept in C language MCQ questions.

30. Which header file is required for using functions like malloc and free?

a) <stdio.h>

b) <stdlib.h>

c) <string.h>

d) <memory.h>

Answer: (b) <stdlib.h>

Explanation: Functions such as malloc and free that can be used to allocate dynamic memory, require inclusion of the  header file to be used. This header file contains the declarations for these functions so that memory can be allocated and deallocated while the program is running. 

Without including <stdlib.h>, the compiler won’t recognize malloc and free, leading to errors. Other header files like <stdio.h>, <string.h>, and <memory.h> serve different purposes, such as input/output operations or string manipulation, but they do not support memory allocation functions. Hence, option (b) <stdlib.h> is the correct answer.

31. What is the default return type of functions in C if not specified?

a) void

b) int

c) float

d) char

Answer: (b) int

Explanation: If you don't declare or specify a return type of a function, the default return type for the function will be an int return type. The function is expected to return an int value unless there is otherwise stated. This is part of the design of C that allows functions to return a value that provides some meaning. 

For example, if you write a function without mentioning the return type, like main(), it is treated as int main() by default. This is why the correct answer is option b) int, as C assumes the return type to be an integer unless you define it differently, such as using void for functions that don’t return anything. This is a common question in C Programming MCQ assessments.

32. Which operator is used for logical AND in C?

a) &

b) &&

c) and

d) All of the above

Answer: (b) &&

Explanation: The logical AND operator combines two conditions and returns true if both conditions are true. The correct operator for this is "&&". For example, if you want to check whether two conditions are both true, you would use "&&" to combine them.

The "&" operator is bitwise AND, which is different from the logical AND, and "and" is not a valid operator in C. Therefore, the correct answer is "&&", as it is the classic way to perform a logical AND in C programming.

33. Which header file is required for using printf() and scanf() functions in C?

a) stdlib.h
b) stdio.h
c) string.h
d) math.h

Answer: b) stdio.h

Explanation: The stdio.h header file contains the declarations of the input/output functions like printf() or scanf(). 

34. Which function is used to read a single character from standard input in C?

a) getchar()
b) gets()
c) scanf()
d) putchar()

Answer: a) getchar()

Explanation: getchar() reads a single character from standard input.

35. Which function is used to calculate the power of a number in C?

a) pow()
b) exp()
c) sqrt()
d) abs()

Answer: a) pow()

Explanation: pow() is declared in math.h and returns the value of one number raised to the power of another.

36. Which header file must be included to use mathematical functions like sin() and cos()?

a) stdlib.h
b) string.h
c) math.h
d) stdio.h

Answer: c) math.h

Explanation: math.h provides declarations for mathematical functions such as sin(), cos(), and sqrt().

37. Which keyword is used to define an enumeration in C?

a) enum
b) typedef
c) struct
d) define

Answer: a) enum

Explanation: The enum keyword is used to declare enumerated types in C.

38. Which of the following statements about typedef is TRUE?

a) typedef creates a variable
b) typedef creates a new data type alias
c) typedef is used for memory allocation
d) typedef is only used with structs

Answer: b) typedef creates a new data type alias

Explanation: typedef allows you to define an alias for an existing data type, improving code readability.

39. What is the output of the following code?

#include <stdio.h>

typedef int myint;

int main() {
    myint a = 5;
    printf("%d", a);
    return 0;
}

a) 0
b) 5
c) Garbage value
d) Compilation error

Answer: b) 5

Explanation: typedef int myint; creates myint as an alias for int.

40. Which of the following is a valid float variable declaration in C?

a) float number;
b) int number;
c) float number = "3.14";
d) double number;

Answer: a) float number;

Explanation: The float data type is used to store decimal numbers.

41. Which operator is used to check if two values are equal in C?

a) =
b) ==
c) !=
d) :=

Answer: b) ==

Explanation: The == operator is a relational operator used to compare equality.

42. What is the result of the expression 5 + 2 * 3 in C?

a) 21
b) 17
c) 11
d) 27

Answer: c) 11

Explanation: Operator precedence dictates that multiplication is performed before addition: 2 * 3 = 6, then 5 + 6 = 11.

43. Which operator is used to determine the size of a variable or data type in bytes?

a) size()
b) sizeof
c) length
d) bytesof

Answer: b) sizeof

Explanation: The sizeof operator returns the size in bytes.

44. Which operator increases the value of a variable by 1?

a) ++
b) --
c) +=
d) **

Answer: a) ++

Explanation: The increment operator (++) increases a variable's value by 1.

Quick Summary: Intermediate C Language MCQs

This section sharpens practical exam-related C concepts every student needs before moving on to other more advanced programming. The section covers important topics like determining memory size using sizeof, performing arithmetic evaluations with precedence, using dynamic memory functions (malloc, free), a default return type, logical operators and headers  (stdio.h, stdlib.h, math.h). You also reinforce fundamentals of enums, typedefs, relational operators, increment operators, and function prototypes.

Together, these questions strengthen core reasoning skills, how C computes expressions, allocates memory, handles input/output, and interprets operators, building the clarity required for debugging, writing predictable code, and clearing intermediate-level technical tests.

45. What does the keyword volatile indicate in C?

a) A variable can change unexpectedly.

b) A variable should not be optimized.

c) A function can be called multiple times.

d) None of the above.

Answer: (a and b) A variable can change suddenly; it should not be optimized.

Explanation: The keyword volatile indicates that a variable's value can change unexpectedly due to external factors like hardware or interrupting service routines. This warns the compiler that the variable should not be optimized, as the value might be updated outside the scope of the current program flow.

Using volatile secures that the compiler does not make assumptions about the variable's value, which could result in errors if optimizations are applied. Therefore, both options a) and b) are correct, as the volatile keyword tells the compiler that the variable's value can change unpredictably and should not be subject to optimization.

46. What will be the output of this code?

#include <stdio.h>

int main() {
    int i = 0;

    while (i < 3)
        printf("%d ", i++);

    return 0;
}

a) Infinite loop

b) Compilation error

c) "0 1 2"

d) "0 1 2 3"

Answer: (c) "0 1 2"

Explanation: The while loop in the example above prints out the value of the variable i, starting at the value of 0. The condition for the loop is i < 3, so it will continue to run while i is less than 3.  Inside the loop, the value of i is printed, and then the i++ operation increments i by 1 after each print.

The loop will print the values 0, 1, and 2 because, after each print, i is incremented, and the loop exits when i reaches 3. Therefore, the output will be "0 1 2". The correct answer is option (c).

47. Which function is used to allocate memory dynamically in C?

a) calloc()

b) malloc()

c) realloc()

d) All of the above

Answer: (d) All of the above

Explanation:Dynamic memory allocation is done using malloc(), calloc(), and realloc(). These functions enable memory to be allocated in runtime, giving programs more flexibility during execution. malloc() allocates memory without initialization, calloc() allocates and initializes memory to zero, and realloc() resizes previously allocated memory.

All three functions serve different purposes but are used for managing dynamic memory, so the correct answer is that all of them are valid.

48. What will be the output of this expression: (5 > 3 && 3 < 4)?

a) True

b) False

c) Compilation error

d) Undefined behavior

Answer: (a) True

Explanation: The expression "(5 > 3 && 3 < 4)" uses the logical AND operator (&&), which checks if both conditions are true. In this case, the first condition "5 > 3" is true, and the second condition "3 < 4" is also true. Since both conditions are true, the logical AND operation will result in true.

Thus, the correct output of this expression will be true. Since both conditions are true, the answer is "a) True." The logical AND operator only returns true when both conditions it checks are true.

49. What does the expression (x << 2) do in C?

a) Divides x by 2
b) Multiplies x by 2
c) Shifts x left by 2 bits (multiplies x by 4)
d) Shifts x right by 2 bits

Answer: c) Shifts x left by 2 bits (multiplies x by 4)

Explanation: Left shift by 2 is equivalent to multiplying the value by 2^2 = 4.

50. What will be the output of the following code?

#include <stdio.h>

int main() {
    int a = 5, b = 3;
    printf("%d", a | b);  // Bitwise OR
    return 0;
}

a) 1
b) 7
c) 8
d) 15

Answer: b) 7

Explanation: 5 (0101) | 3 (0011) = 0111 (7 in decimal).

51. What will be the output of the following code?

#include <stdio.h>

int main() {
    int x = 8;
    printf("%d", x >> 1);  // Right shift by 1 (divides by 2)
    return 0;
}

a) 16
b) 4
c) 8
d) 2

Answer: b) 4

Explanation: Right shifting 8 (1000) by 1 bit results in 4 (0100).

52. What is the result of 12 & 5 in C?

a) 4
b) 5
c) 7
d) 0

Answer: a) 4

Explanation: 12 (1100) & 5 (0101) = 0100 (4 in decimal).

53. Which of the following statements about bitwise operators is TRUE?

a) Bitwise operators can only be used with floating-point numbers.
b) Bitwise operators operate on individual bits of integer operands.
c) Bitwise operators are the same as logical operators.
d) Bitwise operators can be used with strings.

Answer: b) Bitwise operators operate on individual bits of integer operands.

54. What will be the output of the following code?

#include <stdio.h>

int main() {
    printf("%d", printf("C"));  // Prints "C" first, then its length (1)
    return 0;
}

a) C1
b) 1C
c) C2
d) 2C

Answer: a) C1

Explanation: The inner printf prints "C" and returns 1 (the number of characters printed), which is printed by the outer printf.

55. Which function should be used to safely read a string with spaces from input in C?

a) scanf()
b) gets()
c) fgets()
d) strcpy()

Answer: c) fgets()

Explanation: fgets() allows reading a string with spaces and prevents buffer overflow by specifying the maximum number of characters to read.

56. What is the purpose of stdarg.h in C?

a) To handle dynamic memory allocation
b) To handle variable number of arguments in functions
c) To handle string operations
d) To handle mathematical computations

Answer: b) To handle variable number of arguments in functions

Explanation: stdarg.h provides macros for accessing a function's variable argument list.

57. Which function returns a non-zero value if the end of a file is reached in C?

a) feof()
b) ferror()
c) fflush()
d) fopen()

Answer: a) feof()

Explanation: feof() checks the end-of-file indicator for a file stream.

58. Which statement best describes "fall-through" behavior in a switch statement?

a) When a case executes and then always exits the switch
b) When a case executes and continues to the next case without a break
c) When a switch statement is nested inside another switch
d) When the default case is always executed

Answer: b) When a case executes and continues to the next case without a break

Explanation: Fall-through occurs when there is no break statement at the end of a case, causing execution to continue into the next case.

59. What is the effect of the continue statement inside a for loop?

a) Terminates the loop
b) Skips the rest of the code in the current iteration and proceeds to the next iteration
c) Exits the program
d) Restarts the loop from the beginning

Answer: b) Skips the rest of the code in the current iteration and proceeds to the next iteration

Explanation: continue skips the remaining statements in the loop body and proceeds with the next iteration.

60. Which of the following code snippets demonstrates a nested for loop?

a)

#include <stdio.h>

int main() {
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            printf("%d %d\n", i, j);
        }
    }
    return 0;
}

b)

for (int i = 0; i < 2; i++) 
{ 
printf("%d\n", i); 
}

c)

while (1) 
{ 
printf("Hello"); 
}

d)

if (a > b) 
{ 
printf("A");
}

Answer: a)

Explanation: A nested for loop is a for loop inside another for loop.

61. Which statement about labels in C is TRUE?

a) Labels can only be used inside switch statements
b) Labels must be unique within a function
c) Labels are declared with a #define directive
d) Labels can be used outside functions

Answer: b) Labels must be unique within a function

Explanation: Labels are identifiers followed by a colon and must be unique within the same function for use with goto.

62. Which of the following is a correct way to define and use an enum in C?

a) enum color { RED, GREEN, BLUE }; enum color c = GREEN;

b) enum color = { RED, GREEN, BLUE }; color c = GREEN;

c) enum { RED, GREEN, BLUE } color; color = GREEN;

d) typedef enum { RED, GREEN, BLUE } color; color c = GREEN;

Answer: a) and d) are both correct

Explanation: Both forms are valid for defining and using enums, with d) using typedef for aliasing.

63. Which of the following is a benefit of using typedef with structs or enums?

a) Reduces code readability
b) Allows creation of anonymous variables
c) Simplifies the syntax when declaring variables of complex types
d) Prevents use of pointers

Answer: c) Simplifies the syntax when declaring variables of complex types

Explanation: typedef helps avoid repetitive syntax, especially with structs and enums.

64. What does the offsetof macro provide in C?

a) The size of a structure
b) The offset (in bytes) of a member within a structure
c) The address of a variable
d) The number of elements in an array

Answer: b) The offset (in bytes) of a member within a structure

Explanation: offsetof is used to determine how far a member is from the start of a struct.

65. What is the purpose of the fclose() function in C?

a) To open a file
b) To write to a file
c) To close an open file
d) To flush the output buffer

Answer: c) To close an open file

Explanation: fclose() is used to close a file pointer and release resources.

66. Which of the following statements about variable scope is TRUE?

a) A variable declared inside a function is accessible everywhere in the program
b) A variable declared outside all functions is global
c) All variables in C are global by default
d) Variables declared in header files are always local

Answer: b) A variable declared outside all functions is global

Explanation: Such variables have program-wide scope.

67. Which of the following best describes a function call in C?

a) Declaring a function
b) Assigning a value to a variable
c) Using the function name followed by parentheses and arguments
d) Creating a header file

Answer: c) Using the function name followed by parentheses and arguments

Explanation: A function call uses the function name and passes arguments in parentheses.

68. Which keyword is used to suggest that a function should be expanded inline, replacing the function call with the function code itself?

a) const
b) inline
c) restrict
d) static

Answer: b) inline

Explanation: The inline keyword suggests to the compiler to expand the function in place to potentially improve performance.

69. What does the restrict keyword indicate when used with a pointer?

a) The pointer is constant
b) The pointer is stored in a register
c) The pointer is the only reference to the object it points to
d) The pointer is volatile

Answer: c) The pointer is the only reference to the object it points to

Explanation: The restrict keyword indicates that the pointer is the sole means to access the object, enabling optimization.

70. Which keyword is used to declare a pointer variable that may point to hardware registers or memory-mapped I/O, and whose value may change unexpectedly?

a) static
b) volatile
c) restrict
d) const

Answer: b) volatile

Explanation: The volatile keyword is used for pointers or variables whose values can change at any time, such as hardware registers.

71. Which storage class specifier is typically used to define variables with automatic storage duration and block scope?

a) auto
b) static
c) extern
d) register

Answer: a) auto

Explanation: auto is the default storage class for local variables with block scope and automatic storage duration.

72. Which keyword is used to suggest to the compiler that a function should be expanded in place for performance?

a) inline
b) restrict
c) volatile
d) const

Answer: a) inline

Explanation: The inline keyword suggests that the function code should be inserted at each call site.

73. What is the purpose of the restrict keyword in pointer declarations?

a) To declare a constant pointer
b) To allow multiple pointers to the same memory
c) To indicate that the pointer is the only way to access the object it points to
d) To make the pointer volatile

Answer: c) To indicate that the pointer is the only way to access the object it points to

Explanation: restrict enables optimization by telling the compiler no other pointer will access the same memory.

74. Which keyword is used to declare a variable whose value may be changed by hardware or an interrupt service routine?

a) static
b) register
c) volatile
d) const

Answer: c) volatile

Explanation: volatile tells the compiler not to optimize accesses to the variable, as its value can change unexpectedly.

75. Which storage class specifier is used for variables that retain their value between function calls and have static storage duration?

a) auto
b) static
c) register
d) restrict

Answer: b) static

Explanation: static variables inside functions preserve their value between calls and have static storage duration.

76. What is the effect of the #pragma directive in C?

a) It defines a constant
b) It is used for compiler-specific instructions
c) It includes a header file
d) It starts a function declaration

Answer: b) It is used for compiler-specific instructions

Explanation: #pragma gives special instructions to the compiler that are implementation-specific.

77. Which of the following best describes macros in C?

a) They are variables
b) They are functions
c) They are code fragments replaced by the preprocessor
d) They are constants only

Answer: c) They are code fragments replaced by the preprocessor

Explanation: Macros are defined with #define and are replaced before compilation.

78. How does #ifdef enable conditional compilation?

a) It includes code only if a macro is not defined
b) It excludes code if a macro is defined
c) It includes code only if a macro is defined
d) It always includes the code

Answer: c) It includes code only if a macro is defined

Explanation: #ifdef is used to conditionally compile code based on macro definitions.

79. Which preprocessor directive is used to include function declarations from standard libraries?

a) #pragma
b) #define
c) #include
d) #ifdef

Answer: c) #include

Explanation: #include is used to include header files that often contain function declarations.

80. What is the size of a structure with the following members?

struct Test
{ 
int a; 
char b; 
};

a) 5 bytes
b) 8 bytes
c) 4 bytes
d) 6 bytes

Answer: (b) 8 bytes
Explanation: Due to padding/alignment, most systems align int to 4 bytes. Structure becomes:

• int → 4 bytes
• char → 1 byte
• padding → 3 bytes
  Total = 8 bytes.

81. What is the size of the following union?

union Data 
{ 
int a; 
char b; 
double c; 
};

a) sizeof(int) + sizeof(double)
b) sizeof(double)
c) sizeof(char)
d) undefined

Answer: (b) sizeof(double)
Explanation: A union’s size is the size of its largest member. Here, double is the largest.

82. What is the purpose of the stdio.h header file in C?

The stdio.h header file provides declarations for standard input and output functions such as printf(), scanf(), and getchar(). Including this header is essential for any program that performs console input or output.

83. When should I use scanf() versus getchar() for reading input?

Use scanf() when you need to read formatted data (like integers, floats, or strings). Use getchar() when you only need to read a single character from the input stream, such as when processing input one character at a time.

84. Why do I need to include math.h to use functions like sqrt(), pow(), sin(), or cos()?

The header file math.h declares mathematical functions including  sqrt(), pow(), sin(), and cos(). Without math.h,included, the compiler may not exist correctly to those functions and provide compilation errors or warnings. 

85. What does the int main(int argc, char* argv[]) function signature mean?

This form of the main function allows your program to accept command-line arguments. argc is the number of arguments, and argv is an array of strings representing each argument, giving your program flexibility to process input directly from the command line.

86. How do I use stdarg.h and when is it necessary?

The stdarg.h header provides macros to access variadic function arguments. An example of a variadic function is printf(). Use stdarg.h when you want to create functions that can have a varying number of parameters. 

87. What is the difference between printf() and scanf()?

printf() is used to output (print) data to the console, while scanf() is used to read (scan) input from the user. Both are declared in stdio.h and are among the most commonly used C standard library functions.

88. Why is it important to use the correct header files for standard library functions?

Using the correct header files, like stdio.h or math.h, ensures that the compiler knows about the function declarations, their parameters, and return types. This helps prevent compilation errors and undefined behavior.

Quick Summary: Advanced C Programming MCQs

This section concentrates on C concepts that go down to-system level characteristics that affect performance, memory behavior, and low-level control of program behavior. It reinforces how volatile, restrictive, and inline influence compiler optimizations, how dynamic memory (malloc/calloc/realloc) works, and how bitwise operations behave in real execution. You also revisit control flow nuances like fall-through, continue, nested loops, and label usage.

File handling (fclose, feof), preprocessor behavior (#define, #include, #pragma, #ifdef), and enums/typedefs are strengthened with practical MCQs. Struct padding, union memory rules, and macro expansion complete the understanding needed for embedded systems, optimisation-heavy code, and advanced debugging.

Embedded C differs from standard C mainly in how it handles hardware-level tasks. The difference between C and embedded C is that C is used for general-purpose programming, while Embedded C is optimized for microcontrollers, real-time constraints, and direct hardware interaction.

89. In which scenario would you use embedded C programming?

a) For writing desktop applications.

b) For developing firmware for microcontrollers.

c) For web development.

d) For creating mobile applications.

Answer: (b) For developing firmware for microcontrollers.

Explanation: Embedded C programming is used mainly for developing firmware for microcontrollers. These are small, specialized computers that control hardware in devices like cars, medical equipment, and appliances. Embedded C is designed to work directly with the hardware.

In contrast, Embedded C is not used for writing desktop applications, web development, or mobile applications. These tasks are handled by other programming languages such as C++, Java, or Python. Therefore, the correct answer is option b), as Embedded C is specifically made for programming embedded systems like microcontrollers.

90. In Embedded C, which function is used to delay the execution of code?

a) delay()

b) delayms()

c) delay_ms()

d) sleep()

Answer: b) delayms()

Explanation: The delayms() function is often used for creating a time delay in microcontroller applications in embedded systems programming. 

91. Why are bit-fields commonly used in embedded systems?

a) To reduce execution time
b) To reduce memory usage and map hardware registers
c) To speed up file handling
d) To replace unions

Answer: (b) To reduce memory usage and map hardware registers
Explanation: Bit-fields help represent register flags and tightly packed data.

92. What is wrong with the following bit-field declaration?

struct Flags { int flag1 : 33; };

a) Nothing is wrong
b) Bit-field exceeds width of int
c) Bit-fields must be unsigned
d) Bit-fields cannot be inside structures

Answer: (b) Bit-field exceeds the width of int
Explanation: Bit-field width cannot exceed the size of the underlying type.

93. What is the output of this code?

#include <stdio.h>

struct Bits {
    unsigned int a : 4;  // 4-bit wide bit field
};

int main() {
    struct Bits b = { 15 };
    printf("%u", b.a);  // Prints 15
    return 0;
}

a) 15
b) 0
c) 16
d) Undefined

Answer: (a) 15
Explanation: 4-bit unsigned field can store values from 0 to 15.

94. Which structure layout is commonly used for table lookup?

a) Linked list
b) Array of structures
c) Union of integers
d) Pointer to void

Answer: (b) Array of structures
Explanation: Used for lookup tables, configuration tables, and device mapping.

95. Which of the following is TRUE about structure padding in embedded systems?

a) All compilers pad the same way
b) Padding can be disabled or controlled
c) Padding never affects memory
d) Padding only applies to unions

Answer: (b) Padding can be disabled or controlled
Explanation: Using #pragma pack or compiler options.

96. What happens when you assign to one member of a union?

a) All members are updated
b) Other members become uninitialized
c) Other members retain valid values
d) Structure padding changes

Answer: (b) Other members become uninitialized
Explanation: Since all members share memory, writing to one overwrites the others.

97. Who is known as the father of the C programming language?

a) Bjarne Stroustrup

b) Dennis Ritchie

c) James Gosling

d) Linus Torvalds

Answer: b) Dennis Ritchie

Explanation: Dennis Ritchie developed the C language at Bell Labs in the early 1970s. He is usually referred to as the father of C. This fundamental fact is often tested in Cprogramming MCQs.

98. What does %d represent in printf statements?

a) Decimal integer

b) Double data type

c) Dynamic allocation

d) Directory path

Answer: a) Decimal integer

Explanation: %d is used to display decimal integer values in C.

99. Which statement about arrays in C is true?

a) Arrays can store different data types.

b) Array indices start from zero.

c) Arrays cannot be passed to functions.

d) Arrays have dynamic sizes only.

Answer: b) Array indices start from zero.

Explanation: In C, array indices start from 0, which means the first element of the array is accessed with index 0.

100. What will happen if you try to access an array out-of-bounds?

a) It will cause a compilation error.

b) It will cause a runtime error.

c) It may access garbage values or cause undefined behavior.

d) It will return zero.

Answer: c) It may access garbage values or cause undefined behavior.

Explanation: Accessing out-of-bounds memory results in unpredictable behavior, that causes crashes or memory corruption. This concept is frequently tested in C language multiple choice questions.

101. What will be printed by the following code?

#include <stdio.h>
int main()
{  
int i = 4;   
printf("%d", i << 1);    
return 0;
}

a) 4

b) 8

c) 16

d) Compilation error

Answer: b) 8

Explanation: The << operator is a bitwise left shift operator. Turning 4 by 1 bit left results in 8 (binary 100 becomes 1000).

102. Which function would you use to read input from standard input?

a) scanf()

b) getch()

c) getchar()

d) All of these

Answer: d) All of these

ExplanationAll three can be used to read input in C. You might typically use scanf() for input in C while getchar() and getch() are often implemented.

103. What does the following code output?

#include <stdio.h>
int main()
{    
char ptr = "Hello";   
printf("%c", (ptr + 1));  
return 0;
}

a) H

b) e

c) l

d) o

Answer: b) e

Explanation: The pointer called ptr points to the string "Hello". The expression *(ptr + 1) accesses the second character of the string, which is e. This principle is often tested in multiple-choice questions on the C language. 

104. Which of these statements about pointers is false?

a) Pointers can point to any data type.

b) Pointers must be initialized before use.

c) Pointers cannot point to functions.

d) Pointers can point to other pointers.

Answer: c) Pointers cannot point to functions.

Explanation: In C, pointers can point to variables, arrays, and even functions.

105. Which function can be used to concatenate two strings?

a) strconcat()

b) strcat()

c) append()

d) strappend()

Answer: b) strcat()

Explanation: The strcat() function is used to concatenate two strings in C.

Bottom Line:

This section strengthens your fundamentals with high-accuracy C programming coding questions and answers, helping you recall core facts like operators, arrays, pointers, and essential library functions. Mastering these basics ensures you stay confident during exams, interviews, and real debugging scenarios.

To master C programming, you need a good grasp of concepts and the ability to solve problems with C programming Syntax and Operators. You can test your understanding, identify weaknesses, and enhance your skill level by doing C programming multiple-choice questions. Whether you are preparing for exams or interviews and/or you are working on Embedded Systems, these questions can help you get ready for C programming. 

This guide introduces you to some of the most popular and relevant C language MCQ questions, advanced C programming MCQ, basic C programming MCQ with answers, and other specialized topics.

1. What are some common mistakes students make when attempting C programming MCQs?

Many students overlook subtle details in questions, such as pointer initialization, scope of variables, or operator precedence. Others may rush and miss the significance of keywords like static or const. It's important to read each question carefully and understand what is really being asked before choosing an answer.

2. How can I improve my speed and accuracy when solving C MCQs?

Consistent practice is important. Try a variety of questions, Go through the explanations for both correct and incorrect answers, and code small snippets of code to test your understanding. Eventually, you'll, with practice, learn to spot patterns quickly and avoid making common traps. 

3. Why do some C MCQs have more than one correct-looking answer?

C is a language with many small nuances and sometimes questions are great at testing these nuances. Always look for the best answer, which is correct in all instances and compliant with standard C behaviors, rather than seemingly correct at first glance.

4. Do I need to know the latest C standards (like C99 or C11) for MCQs?

Most basic MCQs focus on standard C (often C89/C90), but some advanced or placement-level questions may include features from newer standards. It's helpful to be aware of differences, especially for topics like variable declarations, inline functions, or the restrict keyword.

5. How important are explanations after each MCQ?

Very important! Reading explanations helps reinforce the underlying concept and clears up any misunderstandings. Even if you get a question right, reviewing the explanation can deepen your knowledge and prepare you for trickier variations.

6. What should I do if I consistently get a certain type of C MCQ wrong?

Take it as a cue to revisit that topic in more depth. Study relevant textbook sections, write and run sample code, and seek additional practice questions focused on your weak area. Mastery comes from targeted practice and reflection.

7. Can I rely on MCQs alone to master C programming?

MCQs are a powerful tool for testing knowledge and identifying gaps, but they should be complemented with hands-on coding, debugging, and building small projects. Practical application reinforces what you learn from questions.

8. Is it normal to find pointer and memory management MCQs challenging?

Absolutely. Pointers, memory allocation, and related concepts are among the trickiest parts of C for most learners. Persistent practice, careful tracing of code, and reviewing explanations will gradually build your confidence and skill.