C Programming — MCQ Practice Questions & Answers

Question 1

What will be the size of the following structure? struct test { char c; int i; float f; };

Accepted Answer

Correct answer: D. Depends on padding and alignment — Size depends on compiler's padding and alignment rules. Typically 12 bytes with padding, but varies by system.

Answer

A. 9 bytes

Answer

B. 12 bytes

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C. 13 bytes

Question 2

Which of the following correctly demonstrates pointer arithmetic?

Accepted Answer

Correct answer: A. int *p; p++; — Option A shows pointer arithmetic where p++ increments the pointer by the size of int (4 bytes). Other options are regular arithmetic operations.

Answer

B. int x = 5; x++;

Answer

C. char c = 'a'; c = c + 1;

Answer

D. float f = 3.14; f = f + 1;

Question 3

What is the output of the following code? int a = 5; int *p = &a; int **q = &p; printf("%d", **q);

Accepted Answer

Correct answer: A. 5 — q is a pointer to pointer p. **q dereferences both pointers, giving the value of a, which is 5.

Answer

B. Address of a

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C. Address of p

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D. Compilation error

Question 4

What is true about the variable declared as 'extern int count;' inside a function?

Accepted Answer

Correct answer: B. It refers to a global variable defined elsewhere — extern is a declaration (not definition) that tells compiler the variable exists elsewhere in program. It provides global scope.

Answer

A. It declares a new local variable

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C. It creates a static variable

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D. It's a compilation error

Question 5

Consider a structure with int (4 bytes), char (1 byte), and double (8 bytes). What is the minimum size due to alignment requirements?

Accepted Answer

Correct answer: C. 24 bytes — Due to structure padding/alignment, the size becomes 24 bytes (8-byte alignment for double). Members are padded to maintain alignment.

Answer

A. 13 bytes

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B. 16 bytes

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D. 20 bytes

Question 6

Which of the following statements about type qualifiers is INCORRECT?

Accepted Answer

Correct answer: C. restrict allows pointer aliasing — restrict prevents pointer aliasing (not allows). It tells compiler that pointer is the only way to access that object.

Answer

A. const prevents modification after initialization

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B. volatile prevents compiler optimization

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D. restrict is a C99 feature

Question 7

In the declaration 'volatile int x;', what does volatile signify?

Accepted Answer

Correct answer: A. x can be changed by external factors unexpectedly — volatile tells the compiler that the variable's value may change unexpectedly (e.g., by hardware, signals, or another thread), so the compiler should not optimize it.

Answer

B. x cannot be modified after initialization

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C. x is stored in CPU register for faster access

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D. x is a temporary variable

Question 8

In the declaration 'int *p, q;', what are the data types?

Accepted Answer

Correct answer: B. p is pointer to int, q is int — The '*' applies only to the immediately following variable. So 'int *p' declares p as pointer to int, and 'q' is just an int.

Answer

A. p is int, q is pointer to int

Answer

C. Both are pointers to int

Answer

D. Both are integers

C Programming - MCQ Practice Questions