first working version of ex16

ex16.c

@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct Person {
+    char *name;
+    int age;
+    int height;
+    int weight;
+};
+
+struct Person *Person_create(char *name, int age, int height, int weight)
+{
+    struct Person *who = malloc(sizeof(struct Person));
+    assert(who != NULL);
+
+    who->name = strdup(name);
+    who->age = age;
+    who->height = height;
+    who->weight = weight;
+
+    return who;
+}
+
+void Person_destroy(struct Person *who)
+{
+    assert(who != NULL);
+
+    free(who->name);
+    free(who);
+}
+
+void Person_print(struct Person *who)
+{
+    printf("Name: %s\n", who->name);
+    printf("\tAge: %d\n", who->age);
+    printf("\tHeight: %d\n", who->height);
+    printf("\tWeight: %d\n", who->weight);
+}
+
+int main(int argc, char *argv[])
+{
+    // make two people structures
+    struct Person *joe = Person_create(
+            "Joe Alex", 32, 64, 140);
+
+    struct Person *frank = Person_create(
+            "Frank Blank", 20, 72, 180);
+
+    // print them out and where they are in memory
+    printf("Joe is at memory location %p:\n", joe);
+    Person_print(joe);
+
+    printf("Frank is at memory location %p:\n", frank);
+    Person_print(frank);
+
+    // make everyone age 20 years and print them again
+    joe->age += 20;
+    joe->height -= 2;
+    joe->weight += 40;
+    Person_print(joe);
+
+    frank->age += 20;
+    frank->weight += 20;
+    Person_print(frank);
+
+    // destroy them both so we clean up
+    Person_destroy(joe);
+    Person_destroy(frank);
+
+    return 0;
+}