C++ High Performance

Algorithms operate on iterators

The algorithms in the STL library operate only on iterators, not containers (that is, std::vector, std::map, and so on). Basically, an iterator could be considered an object with the same properties as a regular C-pointer; it can be stepped to the next element and dereferenced (if pointing to a valid address). The algorithms only use a few of the operations that a pointer allows, although the iterator may internally be a heavy object traversing a tree-like std::map.