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

This is an older version of Boost and was released in 2018. The current version is 1.89.0.

buffered_stream::in_avail (1 of 2 overloads)

buffered_stream::in_avail (1 of 2 overloads)

Determine the amount of data that may be read without blocking.

std::size_t in_avail();