containerostream

This header file provides extensions to the iostream << operator so you can pretty print C++ containers. It has a few interesting examples of template metaprogramming and uses some of the more modern C++ (2017) features.

[Vector 4, 2, 17, 14, 15]
[Map a:1, b:2]
(Deque 1, 83, 3, 335, 5)
(T hi, 23, 1.1, (13,bye))

Pedagogical modernization branches

Three branches in this repo show the same library at three points in C++'s evolution. The observable output is byte-identical across all three; the implementations get steadily smaller and more idiomatic.

• master — original C++17 version: 8 operator<< overloads + 2 helper functions.
• cpp20 — collapsed to one template constrained by std::ranges::input_range, plus a tiny style<C> trait for per-container labels. Tuples via std::apply + fold expression.
• cpp23 — most of the library is now redundant: C++23's <format> ships native range and tuple formatters (P2286, P2585). What remains is 3-line std::formatter specializations inheriting from std::range_formatter<T> and calling set_brackets(). Test uses std::println.

See each branch's README for a side-by-side comparison.