The whole size_type <-> size_t malarkey is thanks to STL's gremlins, but that's beyond the point. Every compiler nowadays will emit a warning about comparing/as

The whole size_type <-> size_t malarkey is thanks to STL's gremlins, but that's beyond the point. Every compiler nowadays will emit a warning about comparing/assigning signed and unsigned integers (that can be promoted to an error if need be), as someone's comment already mentioned, which should be enough (not that the C++ warnings are always obvious or easy to parse mentally).