Lots of changes and too much dragging my feet on this. But I think this is going in the right direction now.

includes/array.h

@@ -2,15 +2,17 @@
 #define ARRAY_H
 
 #include <stdbool.h>
+#include <stddef.h>
 
 typedef struct _array {
-    int Capacity;
-    int Size;
+    size_t Capacity;
+    size_t Size;
     void** Items;
 } Array;
 
 Array* ArrayCreate(void);
 bool ArrayAdd(Array* array, void* item);
 void* ArrayPeek(Array* array);
+void* ArrayIndex(Array* array, size_t index);
 
 #endif