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

#define CAPACITY 1024
#define nullptr ((void*)0)

typedef struct {
    char* arr;
    size_t size;
    size_t capacity;
} Vec8_t;

Vec8_t create(const Vec8_t* input) {
    Vec8_t vec = { .arr = nullptr, .size = 0, .capacity = CAPACITY };
    if (input != nullptr && input->size > 0) vec.size = input->size + 1;
    vec.arr = calloc(vec.capacity, sizeof(char));
    return vec;
}

Vec8_t add_back(Vec8_t* vec, const char val) {
    if (vec->size >= vec->capacity) {
        vec->capacity *= 2;
        char* nvec = reallocf(vec->arr, vec->capacity * sizeof(char));
        if (nvec == NULL) return *vec;
        vec->arr = nvec;
    }
    vec->arr[vec->size] = val;
    vec->size++;
    return *vec;
}

// Your current implementation
__attribute__((overloadable)) Vec8_t*
erase(Vec8_t* vec, const int iter_start, const int iter_end) {
        if(vec == nullptr) return nullptr;
        if(vec->arr == nullptr) return nullptr;
        if(iter_start < 0 || iter_end >= vec->size) return nullptr;
        if(iter_start >= iter_end) return nullptr;
        size_t diff = iter_end - iter_start;
        memmove(&vec->arr[iter_start], &vec->arr[iter_end], (vec->size - iter_end) * sizeof(char));
        for(size_t i = vec->size - 1; i > iter_end; i--) {
                vec->arr[i] = 0;
        }
        vec->size -= diff;
        return vec;
}

int main() {
    Vec8_t vec = create(nullptr);
    for (int i = 0; i < 10; i++) add_back(&vec, 'a' + i);
    
    printf("Before erase: ");
    for (int i = 0; i < 10; i++) printf("%c ", vec.arr[i]);
    printf("(size=%zu)\n", vec.size);
    
    erase(&vec, 2, 4);
    
    printf("After erase(2,4): ");
    for (int i = 0; i < 10; i++) printf("%c ", vec.arr[i] == 0 ? '0' : vec.arr[i]);
    printf("(size=%zu)\n", vec.size);
    
    printf("\nExpected: a b e f g h i j (size=8)\n");
    printf("Got:      ");
    for (int i = 0; i < vec.size; i++) printf("%c ", vec.arr[i] == 0 ? '0' : vec.arr[i]);
    printf("(size=%zu)\n", vec.size);
    
    return 0;
}