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

#define N 1
  
typedef struct _acme {
  int data;
} * acme;

int main(void) {
  acme gizmo[N];
  gizmo[0] = (acme)malloc(sizeof(struct _acme));
  size_t msize = malloc_usable_size(gizmo[0]);
  printf("malloc_usable_size(gizmo[0]) %lu\n", msize);
  free(gizmo[0]);
  return (1);
}

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This always allocates 24 bytes - whatever i pass to malloc. I’m a bit confused. What do i miss? Thanks in advance for enlightenment.

Update: Thanks to all for the kind and helpful replies.

«The Crux of the Biscuit is the Apostrophe»

In reply to OT: Why does malloc always give me 24? [SOLVED] by karlgoethebier

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