dynamic array implementation using C.

dynamicArray.c

#include <stdio.h>
#include <stdlib.h>

Arr * create_arr(int max_size) {
    Arr * new_arr = malloc(sizeof(Arr));
    new_arr -> size = 0;
    new_arr -> max_size = 0;
    new_arr -> items = malloc(max_size * sizeof(int));
    if (new_arr -> items != NULL) {
        new_arr -> max_size = max_size;
    }
    return new_arr;
}

void allocate_new_memory_case(Arr * arr) {
    int * tmp_arr = NULL;
    arr -> max_size++;
    // fix realloc: invalid next size.
    tmp_arr = realloc(arr -> items, sizeof(int) * arr -> max_size);
    if (tmp_arr != NULL) {
        arr -> items = tmp_arr;
    } else {
        perror("Error while reallocating arr -> items!!");
        exit(EXIT_FAILURE);
    }
}

void append(int key, Arr * arr) {
    if (arr -> items == NULL) {
        perror("arr -> items is NULL!!");
        exit(EXIT_FAILURE);
    }
    
    if (arr -> size > arr -> max_size) {
        allocate_new_memory_case(arr);
    }
    arr -> items[arr -> size++] = key;
}

void destroy_arr(Arr * arr) {
    free(arr -> items);
    free(arr);
}

dynamicArray.h

struct Arr{
    int * items;
    int size;
    int max_size;
};

typedef struct Arr Arr;

Arr * create_arr(int max_size);
void allocate_new_memory_case(Arr * arr);
void append(int key, Arr * arr);
void destroy_arr(Arr * arr);