Flexible Array Members in Structure

1#include <stdio.h>
2#include <stdlib.h>
3#include <string.h>
4
5struct FlexArray {
6    int size;
7    int data[];  // Flexible array member
8};
9
10struct FlexArray* createArray(int n) {
11    struct FlexArray *arr = malloc(sizeof(struct FlexArray) + n * sizeof(int));
12    arr->size = n;
13    return arr;
14}
15
16int main() {
17    // Create array with 5 elements
18    struct FlexArray *arr = createArray(5);
19    
20    // Fill with data
21    for (int i = 0; i < arr->size; i++) {
22        arr->data[i] = (i + 1) * 10;
23    }
24    
25    printf("Flexible array with %d elements:\n", arr->size);
26    for (int i = 0; i < arr->size; i++) {
27        printf("data[%d] = %d\n", i, arr->data[i]);
28    }
29    
30    printf("\nSize of struct (without array): %zu bytes\n", sizeof(struct FlexArray));
31    printf("Actual allocated: %zu bytes\n", sizeof(struct FlexArray) + arr->size * sizeof(int));
32    
33    free(arr);
34    
35    return 0;
36}