Doc. no.: P0803R0
Date: 2017-10-15
Reply to: Beman Dawes <bdawes at acm dot org>
Audience: Library Evolution

Endian Library Request for Comments (R0)


The Boost Endian library manipulates the endianness of integers and user-defined types. It provides three approaches to dealing with endianness: conversion functions, buffer classes, and arithmetic classes. Each approach has use cases where it is preferred over the other approaches. The purpose of this RFC is to determine interest in adding all or any of these components to the C++ standard library or a library TS.


The Boost Endian documentation ( provides an overview and detailed technical specifications for the conversion functions, arithmetic types, and buffer types.

A separate discussion covers choosing between the three approaches provided by the library.

For those not interested in plowing through the entire documentation, the Overall FAQ, Conversion FAQ, Arithmetic FAQ, and Buffers FAQ answer a lot of question likely to arise during standardization.

Motivation for standardization

Impact on the standard library

All three proposed approaches to endianness would be a pure additions to the standard library and would break no existing user code (modulo the usual namespace caveats).

Proposed wording

The Boost Endian reference documentation for Conversion, Arithmetic, and Buffer approaches follows the standard library's Method of description [description], so provides a fairly close approximation of what proposed wording would look like. Actual proposed wording will be provided in a proposal document for any portions of the library of interest to the committee. Names will need the usual bikeshedding.

Questions for the Library Evolution Group


The original design for the arithmetic classes was developed by Darin Adler based on work by Mark Borgerding. The Boost documentation acknowledges 45+ other people.