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

Returns the value for a field, or "" if it does not exist.

string_view const
operator[](
    field name) const;
  » more...

Returns the value for a case-insensitive matching header, or "" if it does not exist.

string_view const
operator[](
    string_view name) const;
  » more...