What is the difference between struct tag and struct type in C?

The correct answer is B: Tag is the structure name, type is the variable declaration. In 'struct person { int age; } p;', 'person' is the tag (structure name) and 'p' is the type/variable. Tag names the structure template; type creates actual instances.

Which structure feature is most suitable for implementing a state machine with limited states?

The correct answer is A: Bit fields. Bit fields efficiently store boolean/limited-range states using minimal memory, ideal for state machines.

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

The correct answer is A: 4 bytes. Union size equals the largest member size. float is typically 4 bytes, which is largest.

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

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

What is the critical issue if ferror(fp) returns non-zero during file operations in a banking application?

The correct answer is A: An error occurred during file I/O operation that should be handled. ferror() returns non-zero if an error has occurred in file operations. In critical applications like banking, this must be checked to ensure data integrity. This is different from EOF (checked by feof()).

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C Programming
Preprocessor

C language from basics to advanced placement prep

22 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–22 of 22

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.21 Hard Preprocessor

What is the problem with this macro?
#define DOUBLE(x) x*x
int result = DOUBLE(2+3);

A No problem, result is 25

B Result is 11 due to operator precedence

C Compilation error

D Result is undefined

Correct Answer: B. Result is 11 due to operator precedence

EXPLANATION

The macro expands to 2+3*2+3 = 2+6+3 = 11, not 25. This is because x is not parenthesized. Should use #define DOUBLE(x) ((x)*(x))

Test

Q.22 Hard Preprocessor

Which statement about #define is TRUE?

A Macros are type-safe like functions

B Macros do not allocate memory at runtime

C Macros cannot take arguments

D Macros are evaluated at runtime

Correct Answer: B. Macros do not allocate memory at runtime

EXPLANATION

Macros are purely textual substitutions performed by the preprocessor at compile time, not at runtime. They don't allocate memory themselves.

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