Inside the main() function of "particletest.c", we have now allocated an array of 1024 particles of type Particle. As we would like this number to be flexible in the future, the array is allocated dynamically using malloc(), which is part of the C Standard General Utilities Library. Our implementation uses the following approach: #include #include #define NUM_PARTICLES 1024 ··· int main() { Particle *particles = (Particle *)malloc(NUM_PARTICLES); ··· } Despite the fact that the declaration seems correct, the code produces a segmentation fault exception in some experiments. However, in some other situations, no apparent errors are produced. Do you consider the declaration and allocation to be correct (and, thus, the error located somewhere else in the source code)?

Question

BlackTom AI · Accepted Answer

Question restatement: The code allocates an array of 1024 Particle objects using malloc, with the line Particle *particles = (Particle *)malloc(NUM_PARTICLES); inside main. The true/false claim to evaluate is whether the declaration and allocation are correct.

Option 1: True. Why this is not correct: The expression malloc(NUM_PARTICLES) allocates NUM_PARTICLES bytes, not NUM_PARTICLES times the size of a Particle object. Since a Particle is likely larger than 1 byte, this results in under-allocation for an array of 1024 elements. As a consequence, accesses beyond the allocated memory can cause segmentation faults, which matches the observed intermittent crashes. The proper form should be malloc(NUM_PARTICLES * sizeof(Particle)). Additionally, while a cast to (Particle *) is common in C++, it is unnecessary in C; leaving it out is acceptable, but it does not fix the fundamental under-allocation issue.

Option 2: False. Why this is correct: The statement that the declaration and allocation are correct is not true for typical C usage here. The root problem is under-allocation: malloc(NUM_PARTICLES) only reserves NUM_PARTICLES bytes, not NUM_PARTICLES times the size of a Particle. Using malloc(NUM_PARTICLES * sizeof(Particle)) ensures enough memory for 1024 Particle objects. This mismatch between the number of elements and the size of each element is precisely what leads to potential segmentation faults in experiments where a larger Particle structure or different alignment is involved. In short, the declaration is not correct as written because it does not account for the size of Particle.

Option 3 (implicit consideration): If someone argues that the code sometimes works, that would be due to chance and memory layout; still, the general rule remains: you must allocate the total size as count times sizeof(element). The presence of intermittent failures does not validate the buggy approach.

Option 4 (edge consideration): Casting the result of malloc in C is unnecessary and can hide warnings if used incorrectly; however, this does not address the fundamental error of under-allocation. The core issue is the missing sizeof(Particle) factor, not the cast itself.

Summary of reasoning: The under-allocation caused by malloc(NUM_PARTICLES) is the key flaw leading to potential segmentation faults. Correct usage requires allocating NUM_PARTICLES * sizeof(Particle) bytes to safely hold 1024 Particle objects, i.e., Particle *particles = (Particle *)malloc(NUM_PARTICLES * sizeof(Particle)); (or better, Particle *particles = malloc(NUM_PARTICLES * sizeof *particles); in modern C).

DD2360/FDD3360 HT25 (appgpu25) Quiz 1: Basic knowledge

View Explanation

Log in for full answers

Similar Questions

Consider the function call: p = (data_t )malloc((num - 1) sizeof(data_t)) The intention of this function call is best described as:

Which header file must be included to use dynamic memory allocation functions like malloc and free?

Select the true statement

The C realloc function is conventionally used to

If the heap memory location starts at 9403, what is the value of the integer variable myAge at position 1? #include <iostream> using namespace std; int a = 10; int main() { int b; int* myAge = nullptr; b = 20; myAge = new int; // Position 1 *myAge = 30; delete myAge; return 0; }

What does the following code print?#include <iostream> using namespace std; int* allocateMemory() { int ptr = new int; ptr = 10; return ptr; } int main() { int p = allocateMemory(); cout << p << endl; delete p; return 0; }

Which of the following is the correct way to allocate memory dynamically for an integer type array of 10 elements.

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler