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

// ILLUSTRATION OF USING HEAP MEMORY AFTER DEALLOCATING (="freeing")

int main(int argc, char* argv[]) {
    
    int* a_n = malloc(sizeof(*a_n));
    // Allocate space ("allocation block") on the heap sufficient to store an int.
    // Declare a variable 'a_n' as "address of an int".
    // Initialize a_n to the address of the first byte in the new allocation block.

    *a_n = 5;  // Remember:  *α = β means "store value β at address α."
    // Store (value) 5 at (adddress) a_n.

    printf("*a_n == %d\n", *a_n);  // Remember:  *a_n means "value at (address) a_n"
    // Print the value at (address) a_n.

    free(a_n);
    // Deallocate (="free") the heap allocation block at (address) a_n.

    // BAD!!!!!!   Allocation block at (address) a_n was already deallocated (="freed").
    printf("*a_n == %d\n", *a_n);  // NOT DEPENDABLE


    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */