Structs, unions, enumsGrouping fields into a record, and what the compiler does with it.0/60 / 6 required2 to 3
Headers and the preprocessorSplitting a program across files, and what the preprocessor pastes.0/30 / 3 required2 to 4
Linked listsIn progressRe-linking nodes, and walking a chain you cannot index.3/43 / 4 required3 to 4
Stacks, queues, treesAn abstract data type is an interface plus an invariant.0/30 / 3 required4 to 5
Generic codeIn progressFunction pointers, comparators, and a pointer plus a size.0/30 / 3 required4 to 5