alloc.h

       /* Copyright 1987  Pugh-Killeen Associates */
       #define free(x) my_free(x)
       #define calloc(a,b)  my_calloc(a,b)
       void *my_free();
       void *my_calloc();

   alloc.c

/* Copyright 1987  Pugh-Killeen Associates */
#include "alloc.h"
#include <stdio.h>

#undef calloc                      /* Get rid of prior defines */
#undef free                

#define MAX_POINTS 200             /* Maximum number of allocations */

static void *points[MAX_POINTS];   /* Points to allocated memory */
static int point_count;            /* Current index into points */    
static long used;                  /* Number of bytes allocated */

void *calloc();

void *my_calloc(a,b)
/* Allocate and keep track of allocations */
int a;
int b;
    {
    void *pc;
    pc = calloc(a,b);            
    if (pc != NULL)
        {
        used += (long) a * (long) b;
        if (point_count < MAX_POINTS)
            points[point_count++] = pc;
        else
            printf("\n Too many allocations to keep track off");
        }
    else
        printf("\n No memory left , counter = %d used %ld",
           point_count, used);
    return pc;
    }

my_free(pc)    
void *pc;
    {
    int i;
    if (pc == NULL)
        {
        printf("Freeing NULL pointer");    
        goto end;
        }
    /* See which block was allocated */
    for (i = 0; i < point_count; i++)
        {
        if (points[i] == NULL)
            continue;
        else if (points[i] == pc)
            {
            free(pc);
            points[i] = NULL;
            goto end;
            }
        }
    printf("Freeing something not allocated");
end:        
    return;
    }