vec.c

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

struct vec {
  size_t size, cpcty;
  int *arr;
};

typedef struct vec Vec;

Vec *vec_new(size_t size) {
  Vec *v = (Vec *)malloc(sizeof(Vec));
  v->size = size;
  v->cpcty = size;
  v->arr = (int *)calloc(size, sizeof(int));
  return v;
}

void vec_print(Vec *v) {
  for (size_t i = 0; i < v->size; i++)
    printf("%d ", v->arr[i]);
  printf("(size: %lu, capacity: %lu)\n", v->size, v->cpcty);
}

Vec *vec_from_array(int arr[], size_t size) {
  Vec *v = vec_new(size);
  for (size_t i = 0; i < size; i++)
    v->arr[i] = arr[i];
  return v;
}

void vec_add(Vec *v, int val) {
  if (v->size == v->cpcty) {
    v->cpcty *= 2;
    v->arr = realloc(v->arr, sizeof(int) * v->cpcty);
  }
  v->arr[v->size++] = val;
}

int vec_find(Vec *v, int val) {
  for (size_t i = 0; i < v->size; i++)
    if (v->arr[i] == val)
      return i;
  return -1;
}

int vec_at(Vec *v, size_t index) { return v->arr[index]; }

void vec_free(Vec *v) {
  free(v->arr);
  free(v);
}

int main() {
  int arr[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  Vec *v = vec_from_array(arr, 11);
  vec_print(v);
  vec_add(v, 20);
  vec_add(v, 30);
  vec_print(v);
  printf("%d - %d - %d\n", vec_at(v, 3), vec_find(v, 40), vec_find(v, 10));
  vec_free(v);
  return 0;
}