add heap allocation example.

1 files changed, 59 insertions, 0 deletions

diff --git a/heap_example.c b/heap_example.c
new file mode 100644
index 0000000..bc587eb
--- /dev/null
+++ b/heap_example.c
@@ -0,0 +1,59 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+int main(int argc, const char *argv[])
+{
+  char *char_ptr;
+  int *int_ptr;
+  int mem_size;
+
+  if (argc < 2)
+    mem_size = 50;
+  else
+    mem_size = atoi(argv[1]);
+
+  printf("\t[+] allocating %d bytes of memory on the heap for char_ptr\n", mem_size);
+  char_ptr = (char *) malloc(mem_size);
+
+  if (char_ptr == NULL) {
+    fprintf(stderr, "error: could not allocate heap memory.\n");
+    exit(-1);
+  }
+
+  strcpy(char_ptr, "this memory is located on the heap.");
+  printf("char_ptr (%p) --> '%s'\n", char_ptr, char_ptr);
+
+  printf("\t[+] allocating 12 bytes of memory on the heap for int_ptr\n");
+  int_ptr = (int *) malloc(12);
+
+  if (int_ptr == NULL) {
+    fprintf(stderr, "Error: could not allocate heap memory.\n");
+    exit(-1);
+  }
+
+  *int_ptr = 31337;
+  printf("int_ptr (%p) --> %d\n", int_ptr, *int_ptr);
+
+  printf("\t[-] freeing char_ptr's heap memory...\n");
+  free(char_ptr);
+
+  printf("\t[+] allocating another 15 bytes for char_ptr\n");
+  char_ptr = (char *)malloc(15);
+
+  if (char_ptr == NULL) {
+    fprintf(stderr, "Error: could not allocate heap memory.\n");
+    exit(-1);
+  }
+
+  strcpy(char_ptr, "new memory");
+  printf("char_ptr (%p) --> '%s'\n", char_ptr, char_ptr);
+
+  printf("\t[-] freeing int_ptr's heap memory...\n");
+  free(int_ptr);
+  printf("\t[-] freeing char_ptr's heap memory...\n");
+  free(char_ptr);
+
+  return 0;
+}