Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Inequality operator.

bool
operator!=(
    const rows& lhs,
    const rows& rhs);

No-throw guarantee.

Linear in lhs.size() * lhs.num_columns() and rhs.size() * rhs.num_columns().