A simple moving average implementation in C using a struct object

moving_average.c

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

typedef struct moving_average
{
    float *buffer;
    int length;
    float sum;
    int pos;
    bool is_filled;
}moving_average_t;

float moving_average_fct(moving_average_t * av_obj, float new_element)
{
  //Subtract the oldest number from the prev sum, add the new number
  av_obj->sum = av_obj->sum - av_obj->buffer[av_obj->pos] + new_element;
  //Assign the nextNum to the position in the array
  av_obj->buffer[av_obj->pos] = new_element;
  //Increment position internaly
  av_obj->pos++;
  if (av_obj->pos >= av_obj->length){
    av_obj->pos = 0;
    av_obj->is_filled = true;
  }
  //return the average
  return av_obj->sum / (float)(av_obj->is_filled ? av_obj->length:av_obj->pos);
}

moving_average_t * alloc_moving_average_obj(int len)
{
    moving_average_t * av_obj = malloc(sizeof(moving_average_t));
    av_obj->sum       = 0;
    av_obj->pos       = 0;
    av_obj->length    = len;
    av_obj->is_filled = false;
    av_obj->buffer = calloc(len, sizeof(float));
    return av_obj;
}

void free_moving_average_obj(moving_average_t * av_obj)
{
    free(av_obj->buffer);
    av_obj->buffer = NULL;
    free(av_obj);
}

int main()
{
    // a sample array of numbers. The represent "readings" from a sensor over time
    int sample[] = {50, 10, 20, 18, 20, 100, 18, 10, 13, 500, 50, 40, 10};
    // the size of this array represents how many numbers will be used
    // to calculate the average

    
    float average_value = 0;
    int count = sizeof(sample) / sizeof(int);
    
    moving_average_t * sensor_av = alloc_moving_average_obj(5);
    
    for(int i = 0; i < count; i++){
        average_value = moving_average_fct(sensor_av, sample[i]);
        printf("The new average is %2.2f\n", average_value);
    }
    
    free_moving_average_obj(sensor_av);
    sensor_av = NULL;

    return 0;
}