Re: [Mingw-users] How to printf long doubles

[Keith M. <kei...@us...>]

On Saturday 13 December 2008 02:22:02 JonY wrote:
> > Google will only tell me that "%Lf" is broken on MinGW (as of a
> > few years ago), and the wiki has been removed.

It isn't so much that "%Lf" is broken, as that MSVCRT doesn't 
differentiate between `long double' and `double'.  Both are treated 
as being 64-bit; however, MinGW has 80-bit `long double'.

> Try adding "-D__USE_MINGW_ANSI_STDIO" to gcc when compiling it.

mingwrt-3.15 onwards[*] provides a fully ANSI conformant printf(); 
however, it isn't used by default, unless you compile with `-ansi', 
`-posix' or, as JonY suggests, `-D__USE_MINGW_ANSI_STDIO'.

Regards,
Keith.

[*] Earlier mingw-runtime versions didn't support this; you could, 
however, use snprintf() to get 80-bit `long double' interpretation.