advanced patterns when using realloc with a struct containing dynamic arrays in C
I'm stuck on something that should probably be simple. I'm working with an scenario when trying to resize an array within a struct using `realloc`. My struct contains a dynamically allocated array, and I want to expand this array when needed. However, whenever I use `realloc`, I seem to be losing access to the previously allocated memory, and I end up with garbage values or segmentation faults. Here's a simplified version of my code: ```c #include <stdio.h> #include <stdlib.h> typedef struct { int *data; size_t size; } IntArray; IntArray* create_array(size_t initial_size) { IntArray *arr = malloc(sizeof(IntArray)); arr->data = malloc(initial_size * sizeof(int)); arr->size = initial_size; return arr; } void resize_array(IntArray *arr, size_t new_size) { int *temp = realloc(arr->data, new_size * sizeof(int)); if (temp) { arr->data = temp; arr->size = new_size; } else { // Handle realloc failure fprintf(stderr, "Failed to resize array\n"); } } int main() { IntArray *arr = create_array(5); for (size_t i = 0; i < arr->size; i++) { arr->data[i] = i * 10; } resize_array(arr, 10); for (size_t i = 0; i < arr->size; i++) { printf("%d ", arr->data[i]); } printf("\n"); free(arr->data); free(arr); return 0; } ``` When I run this code, I expect to see the values from the original array followed by zeros for the newly allocated space. Instead, I often see garbage values in the output. I've checked the return value from `realloc`, and it seems to be succeeding, but I suspect there might be an scenario with the way I'm managing memory. Additionally, I've tried initializing the new memory to zero by using `calloc`, but that approach does not help with the garbage values when I access the older indices. Is there something I'm missing in my memory management that could lead to this behavior? Any suggestions would be appreciated! This issue appeared after updating to C 3.9. Thanks in advance! I'm working in a Ubuntu 20.04 environment.