---

#include <stdio.h>
#include <malloc.h> /* for definition of ptrdiff_t on GLIBC */
#include <unistd.h>
#include <alloca.h> /* for demonstration only */
extern void afunc(void); /* a function for showing stack growth */
int bss_var; /* auto init to 0, should be in BSS */
int data_var = 42; /* init to nonzero, should be data */
int
main(int argc, char **argv) /* arguments aren't used */
{
char *p, *b, *nb;
printf("Text Locations:\n");
printf("\tAddress of main: %p\n", main);
printf("\tAddress of afunc: %p\n", afunc);
printf("Stack Locations:\n");
afunc();
p = (char *) alloca(32);
if (p != NULL) {
printf("\tStart of alloca()'ed array: %p\n", p);
printf("\tEnd of alloca()'ed array: %p\n", p + 31);
}
printf("Data Locations:\n");
printf("\tAddress of data_var: %p\n", & data_var);
printf("BSS Locations:\n");
printf("\tAddress of bss_var: %p\n", & bss_var);
b = sbrk((ptrdiff_t) 32); /* grow address space */
nb = sbrk((ptrdiff_t) 0);
printf("Heap Locations:\n");
printf("\tInitial end of heap: %p\n", b);
printf("\tNew end of heap: %p\n", nb);
b = sbrk((ptrdiff_t) -16); /* shrink it */
nb = sbrk((ptrdiff_t) 0);
printf("\tFinal end of heap: %p\n", nb);
}
void
afunc(void)
{
static int level = 0; /* recursion level */
auto int stack_var; /* automatic variable, on stack */
if (++level == 3) /* avoid infinite recursion */
return;
printf("\tStack level %d: address of stack_var: %p\n",
level, & stack_var);
afunc(); /* recursive call */
}