Calculating the Correct Size of a Structure Array with Flexible Member in C
I'm getting frustrated with I've been struggling with this for a few days now and could really use some help. I've searched everywhere and can't find a clear answer. I'm working with a structure that contains a flexible array member, and I'm running into a question when trying to calculate the size of an array of these structures. My struct looks like this: ```c typedef struct { size_t count; int values[]; } IntArray; ``` I want to create multiple instances of `IntArray`, and I'm dynamically allocating enough memory to include the flexible member. However, I keep working with an scenario when I attempt to access the `values` array in the second instance. Here’s how I’m allocating memory: ```c IntArray *create_array(size_t count) { IntArray *array = malloc(sizeof(IntArray) + (count - 1) * sizeof(int)); if (!array) return NULL; array->count = count; return array; } ``` When I call `create_array(5)` and then attempt to set values in the first instance like so: ```c IntArray *array1 = create_array(5); for (size_t i = 0; i < array1->count; i++) { array1->values[i] = i * 10; } ``` I can correctly retrieve those values. But when I create a second instance with `IntArray *array2 = create_array(3);` and try to access `array2->values[0]`, I get a segmentation fault. Here’s the code snippet for that: ```c IntArray *array2 = create_array(3); if (array2) { printf("First value: %d\n", array2->values[0]); // Segmentation fault here } ``` I've double-checked the size calculations, and I believe I’m allocating the right amount of memory relative to the count parameter. Am I missing something in how I'm handling the flexible array member? I’m using GCC version 11.2.0, and I've also tried running it with Address Sanitizer, but no additional issues were reported. What am I doing wrong? How would you solve this? I'm working on a application that needs to handle this. What's the best practice here? What am I doing wrong? What's the correct way to implement this?