COLLECTIONS
------------------
array      int array[] = { … }
           random access    //   array[i] = 3;
           all elements must be the same type  //  array[i] = "abc";   NO!!!
           refer to an array by one name

struct     Point p = { … }
           random access   // point.x
           elements may be different types
           refer to a struct object by one name

linked list  
           sequential access  // start with first node and hope from one to another
           elements must be same type
           refer to a linked list by name of the first node.
           ENABLES:  insert, delete, reorder … without copying all of the data

-----------------
NOT SERIOUS

pseuso-array    int n1 = 10;
                int n2 = 11;
                int n3 = 12;