1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | #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: */
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