1. What is the correct syntax to declare a pointer in C?
- a) int ptr*;
- b) *int ptr;
- c) int *ptr;
- d) ptr int*;
Answer: C - The correct syntax is data type followed by asterisk then pointer name (int *ptr).
2. Which of these is NOT a valid C keyword?
- a) volatile
- b) register
- c) string
- d) typedef
Answer: C - "string" is not a keyword in C, though it can be implemented using character arrays.
3. What is the output of sizeof(int) on a 32-bit system?
- a) 2 bytes
- b) 4 bytes
- c) 8 bytes
- d) Compiler dependent
Answer: B - On 32-bit systems, sizeof(int) is typically 4 bytes.
4. Which operator has the highest precedence in C?
- a) &&
- b) ||
- c) ()
- d) =
Answer: C - Parentheses () have the highest precedence in C.
5. What is the purpose of the #include directive?
- a) To link libraries
- b) To include header files
- c) To define macros
- d) To declare variables
Answer: B - #include is used to include the contents of header files in the source code.
6. Which function is used to allocate memory dynamically?
- a) malloc()
- b) calloc()
- c) realloc()
- d) All of the above
Answer: D - All these functions are used for dynamic memory allocation in C.
7. What is the default return type of a function in C?
- a) void
- b) int
- c) float
- d) char
Answer: B - If no return type is specified, the function defaults to returning int.
8. Which of these is NOT a storage class in C?
- a) auto
- b) register
- c) dynamic
- d) static
Answer: C - "dynamic" is not a storage class in C. The storage classes are auto, register, static, and extern.
9. What is the correct way to initialize an array in C?
- a) int arr[] = {1, 2, 3};
- b) int arr[3] = {1, 2, 3};
- c) int arr[3]; arr = {1, 2, 3};
- d) Both a and b
Answer: D - Both a and b are correct ways to initialize an array in C.
10. What does the 'break' statement do in a switch case?
- a) Terminates the program
- b) Exits the switch statement
- c) Continues to the next case
- d) Restarts the switch statement
Answer: B - The break statement exits the switch statement, preventing fall-through to other cases.
11. What is the output of: printf("%d", 5 + 2 * 3);
- a) 21
- b) 11
- c) 15
- d) 17
Answer: B - Due to operator precedence, multiplication is done first (2*3=6) then addition (5+6=11).
12. Which header file is required for using printf() and scanf()?
- a) conio.h
- b) math.h
- c) stdio.h
- d) stdlib.h
Answer: C - stdio.h (Standard Input Output header file) contains declarations for printf() and scanf().
13. What is the purpose of the 'void' keyword in function parameters?
- a) To indicate no parameters
- b) To indicate variable parameters
- c) To indicate any type of parameters
- d) To indicate pointer parameters
Answer: A - void in function parameters indicates that the function takes no arguments.
14. What is the correct way to declare a constant in C?
- a) constant int x = 5;
- b) #define x 5
- c) const int x = 5;
- d) Both b and c
Answer: D - Constants can be declared using either #define or the const keyword.
15. What is the range of values for a signed char in C?
- a) 0 to 255
- b) -127 to 127
- c) -128 to 127
- d) 0 to 127
Answer: C - A signed char typically uses two's complement representation with range -128 to 127.
16. Which of these is NOT a valid variable name in C?
- a) _var
- b) 2var
- c) var2
- d) var_name
Answer: B - Variable names cannot start with a digit in C.
17. What is the purpose of the 'extern' keyword?
- a) To declare a global variable
- b) To extend the visibility of a variable
- c) To make a variable constant
- d) To allocate memory dynamically
Answer: B - 'extern' is used to declare a variable that is defined in another file or later in the same file.
18. What is the output of: printf("%d", sizeof('a'));
- a) 1
- b) 2
- c) 4
- d) Compiler dependent
Answer: C - In C, character constants are of type int, so sizeof('a') is typically 4 bytes.
19. Which loop is guaranteed to execute at least once?
- a) for
- b) while
- c) do-while
- d) All of the above
Answer: C - The do-while loop checks the condition after executing the body, so it always executes at least once.
20. What is the purpose of the 'volatile' keyword?
- a) To optimize variable access
- b) To prevent compiler optimization
- c) To make a variable constant
- d) To allocate memory in CPU registers
Answer: B - 'volatile' tells the compiler that the variable may change unexpectedly, preventing optimization.