Which of the following correctly initializes a structure array? struct point { int x, y; } arr[3] = ?

The correct answer is A: { {1,2}, {3,4}, {5,6} }. Structure arrays are initialized with nested braces, where each set of braces contains initialization values for one structure element.

What will be printed by the following code? #include int main() { char str[] = "Hello"; printf("%c", str[1]); return 0; }

The correct answer is B: e. String indexing starts at 0. str[0] = 'H', str[1] = 'e'.

What is the primary purpose of using functions in C programming?

The correct answer is A: To modularize code and improve reusability. Functions allow code reusability, modularity, and easier maintenance. They break down complex problems into smaller, manageable pieces.

What is the purpose of function inlining in modern C compilers?

The correct answer is B: To reduce function call overhead by replacing calls with function body. Inlining substitutes a function call with the actual function body at compile time, eliminating function call overhead. This is a compiler optimization for performance-critical code.

What happens when you assign a larger data type value to a smaller one?

The correct answer is B: Implicit type conversion (with possible data loss). C allows implicit type conversion. When assigning larger to smaller type, truncation or data loss may occur without any compiler error.

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C Programming
Structures & Unions

C language from basics to advanced placement prep

46 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 41–46 of 46

Topics in C Programming

All Basics & Syntax 86 Data Types & Variables 97 Control Flow 100 Functions 99 Arrays & Strings 100 Pointers 99 Structures & Unions 100 File Handling 100 Dynamic Memory 98 Preprocessor 99

Q.41 Medium Structures & Unions

What is the purpose of padding in structures?

A To waste memory intentionally

B To align data for faster CPU access

C To prevent hacking

D To increase security

Correct Answer: B. To align data for faster CPU access

EXPLANATION

Padding ensures that structure members are aligned in memory according to their natural boundaries, improving CPU access speed.

Test

Q.42 Medium Structures & Unions

How do you access a member of a structure using a pointer?

A ptr.member

B ptr->member

C *ptr.member

D ptr*member

Correct Answer: B. ptr->member

EXPLANATION

The arrow operator (->) is used to access structure members through a pointer. Dot (.) is for direct variables.

Test

Q.43 Medium Structures & Unions

What will be printed?
struct s { int a; char b; int c; }; printf("%lu", sizeof(struct s));

A 9 bytes

B 12 bytes

C 13 bytes

D 8 bytes

Correct Answer: B. 12 bytes

EXPLANATION

Due to memory alignment/padding: int a(4) + char b(1) + 3 padding bytes + int c(4) = 12 bytes.

Test

Q.44 Medium Structures & Unions

What is the difference between struct and typedef struct?

A No difference, both are identical

B typedef struct allows direct variable declaration without 'struct' keyword

C struct is faster than typedef struct

D typedef struct is used only in C++

Correct Answer: B. typedef struct allows direct variable declaration without 'struct' keyword

EXPLANATION

typedef struct creates an alias, so you can declare variables directly using the alias name without repeating 'struct'.

Test

Q.45 Medium Structures & Unions

Which of the following correctly declares a pointer to a structure?

A struct emp *ptr;

B *struct emp ptr;

C struct *emp ptr;

D emp struct *ptr;

Correct Answer: A. struct emp *ptr;

EXPLANATION

Correct syntax is 'struct typename *pointerName;'. Option A follows proper declaration syntax.

Test

Q.46 Medium Structures & Unions

What happens when you initialize a structure variable without assigning values?

A Members are automatically set to 0

B Members contain garbage values

C Compilation error occurs

D Members are set to NULL

Correct Answer: B. Members contain garbage values

EXPLANATION

Uninitialized local structure variables contain garbage values. Global structures are automatically initialized to zero.

Test

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C Programming Structures & Unions

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Structures & Unions