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C Programming

C language from basics to advanced placement prep

303 Q 10 Topics Take Test

Difficulty: All Easy Medium Hard 91–100 of 303

Topics in C Programming

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

Q.91 Easy Structures & Unions

What is the primary difference between a struct and a union in C?

A Struct members are stored sequentially; union members share the same memory location

B Union members are stored sequentially; struct members share memory

C Both allocate separate memory for each member

D There is no functional difference

Correct Answer: A. Struct members are stored sequentially; union members share the same memory location

EXPLANATION

In a union, all members occupy the same memory space, while struct members have individual memory locations.

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Q.92 Easy Structures & Unions

Consider the following code:
struct Data {
int a;
char b;
};
struct Data d = {10, 'A'};
Which method of initialization is used here?

A Designated initialization

B Positional initialization

C Named initialization

D Array initialization

Correct Answer: B. Positional initialization

EXPLANATION

Values are assigned in the order they appear in the structure definition, which is positional initialization.

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Q.93 Easy Structures & Unions

Which of the following statements about structures is TRUE?

A A structure is a collection of variables of the same data type

B A structure is a collection of variables of different data types grouped under a single name

C A structure cannot contain pointers

D A structure occupies memory equal to the sum of its members without any padding

Correct Answer: B. A structure is a collection of variables of different data types grouped under a single name

EXPLANATION

A structure allows grouping of different data types. Padding may be added by the compiler for alignment.

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Q.94 Easy Structures & Unions

Which of the following is the correct way to initialize a structure in C?

A struct Point p = {10, 20};

B struct Point p; p = {10, 20};

C Point p = {10, 20};

D p.x = 10; p.y = 20; (without declaration)

Correct Answer: A. struct Point p = {10, 20};

EXPLANATION

Structures must be initialized at declaration time using curly braces. Assignment of initializer list is not valid after declaration.

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Q.95 Easy Structures & Unions

Which of the following correctly demonstrates a typedef for a structure?

A typedef struct { int x; int y; } Point;

B struct typedef Point { int x; int y; };

C define struct Point { int x; int y; };

D struct Point typedef { int x; int y; };

Correct Answer: A. typedef struct { int x; int y; } Point;

EXPLANATION

The correct syntax for typedef struct is: typedef struct { members } StructName;

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Q.96 Easy Structures & Unions

How do you access a member of a structure through a pointer in C?

A Using dot operator (.)

B Using arrow operator (->)

C Using asterisk (*)

D Using ampersand (&)

Correct Answer: B. Using arrow operator (->)

EXPLANATION

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

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Q.97 Easy Structures & Unions

Consider: union Data { int i; float f; char c; }; What is the size of this union?

A 4 bytes

B 9 bytes

C 5 bytes

D 12 bytes

Correct Answer: A. 4 bytes

EXPLANATION

The size of a union equals the size of its largest member. Here, int is 4 bytes (largest), so union size is 4 bytes.

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Q.98 Easy Structures & Unions

Which of the following statements about unions is correct?

A Union members share the same memory location

B Union size equals the sum of all member sizes

C All union members can hold values simultaneously

D Union requires more memory than structure

Correct Answer: A. Union members share the same memory location

EXPLANATION

Union members share the same memory location, and the union size equals the size of its largest member.

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Q.99 Easy Structures & Unions

What is the correct way to dynamically allocate an array of structures?
struct Student { int roll; char name[50]; };

A struct Student *arr = (struct Student*)malloc(n * sizeof(struct Student));

B struct Student arr = (struct Student*)malloc(n * sizeof(char));

C struct Student *arr = malloc(n);

D Student *arr = malloc(n * Student);

Correct Answer: A. struct Student *arr = (struct Student*)malloc(n * sizeof(struct Student));

EXPLANATION

Correct allocation requires pointer declaration, proper cast, and multiplying n with sizeof(struct Student).

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Q.100 Easy Structures & Unions

When structure is passed by value to a function, which of these is true?

A Changes to structure members inside function affect the original

B The entire structure is copied onto the stack

C Only pointers within the structure are copied

D Memory is shared between function and caller

Correct Answer: B. The entire structure is copied onto the stack

EXPLANATION

Pass by value creates a complete copy of the structure on the function's stack frame.

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