The GNU library's float<->string routines are based on David Gay's. Therefore you can compare those to Gay's originals to see how mucheffort was required to make them "mostly" portable, and can look at thehistory of those to get some feel for the maintenance burden.There's no difficulty in doing this correctly except for denormals.  Thepain is almost entirely in doing it correctly /fast/ -- and that isindeed hard (which accounts for the extreme length and complexity ofGay's code).