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.

Which of the following about function declaration and definition is TRUE?

The correct answer is B: A function can be declared multiple times but defined only once. Functions can have multiple forward declarations but only one definition. This allows function prototypes in header files.

In a nested structure, how do you access the innermost member? struct outer { struct inner { int value; } in; } obj;

The correct answer is B: obj.in.value. For nested structures accessed through an object, use the dot operator multiple times: obj.in.value accesses the value member of the inner structure.

In competitive programming for GATE/ISRO 2025, which scenario would union be preferable over structure?

The correct answer is B: When memory optimization is critical and you need mutually exclusive data. Unions are preferred when you have mutually exclusive data (only one member is used at a time) and memory is critical. A classic example is storing different data types in a tagged union pattern used in compilers and interpreters.

What will be printed by this code? struct s { int a; struct s *next; }; struct s *ptr; sizeof(struct s)

The correct answer is C: 12 bytes. sizeof(int) = 4 bytes, sizeof(pointer) = 8 bytes (on 64-bit systems). Total = 12 bytes. Pointers are fixed size regardless of what they point to.

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C Programming
File Handling

C language from basics to advanced placement prep

21 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–21 of 21

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 File Handling

Write a code snippet to read 100 bytes from a file. Which is correct?

A fread(buffer, 1, 100, fp);

B fread(buffer, 100, 1, fp);

C fread(buffer, 100, fp);

D fread(100, buffer, fp);

Correct Answer: A. fread(buffer, 1, 100, fp);

EXPLANATION

fread() syntax is fread(ptr, size, count, stream). To read 100 bytes, size=1 and count=100. Option B reads 100 items of 1 byte each, which is equivalent but less clear.

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C Programming File Handling

C Programming
File Handling