Page History

#include <stdlib.h>

typedef struct gadget gadget;
struct gadget {
  int i;
  double d;
};

typedef struct widget widget;
struct widget {
  char c[10];
  int i;
  double d;
};

widget *p;

/* ... */

p = malloc(sizeof(gadget)); /* imminent problem */
if (p != NULL) {
  p->i = 0;               /* undefined behavior */
  p->d = 0.0;             /* undefined behavior */
}

widget *p;

/* ... */

p = (widget *)malloc(sizeof(widget));

/* allocates a single object using malloc(). */
#define MALLOC(type) ((type *)malloc(sizeof(type)))

/* allocates an array of objects using malloc(). */
#define MALLOC_ARRAY(number, type) \
    ((type *)malloc((number) * sizeof(type)))

/* allocates a single object with a flexible
 * array member using malloc(). */
#define MALLOC_FLEX(stype, number, etype) \
    ((stype *)malloc(sizeof(stype) \
    + (number) * sizeof(etype)))

/* allocates an array of objects using calloc(). */
#define CALLOC(number, type) \
    ((type *)calloc(number, sizeof(type)))

/* reallocates an array of objects using realloc(). */
#define REALLOC_ARRAY(pointer, number, type) \
    ((type *)realloc(pointer, (number) * sizeof(type)))

/* reallocates a single object with a flexible
 * array member using realloc(). */
#define REALLOC_FLEX(pointer, stype, number, etype) \
    ((stype *)realloc(pointer, sizeof(stype) \
    + (number) * sizeof(etype)))

enum month { Jan, Feb, /* ... */ };
typedef enum month month;

typedef struct date date;
struct date {
  unsigned char dd;
  month mm;
  unsigned yy;
};

typedef struct string string;
struct string {
  size_t length;
  char text[];
};

date *d, *week, *fortnight;
string *name;

d = MALLOC(date);
week = MALLOC_ARRAY(7, date);
name = MALLOC_FLEX(string, 16, char);
fortnight = CALLOC(14, date);