bug? floating point precision with std.format

[Seb via Digitalmars-d]

On Monday, 5 June 2017 at 15:37:42 UTC, Steven Schveighoffer 
wrote:
> It appears that the precision parameter in std.format differs 
> from its meaning in printf. Is that expected behavior?
>
> Example:
>
> import std.stdio;
> import core.stdc.stdio;
>
> void main()
> {
>     auto f = 20.66666;
>     writeln(f);
>     writefln("%0.3s", f);
>     printf("%0.3f\n", f);
> }
>
> prints:
> 20.6667
> 20.7
> 20.667
>
> It appears that the precision specifier is dictating the total 
> number of digits on *both sides* of the decimal place. Whereas, 
> in C, it's only the number of digits *after* the decimal place.
>
> I'm trying to specify 3 places of precision after the decimal. 
> How do I do this easily?
>
> I'm having a hard time believing this behavior has never been 
> reported, but I can't find anything about it in bugzilla. 
> Tested all the way back to 2.040.
>
> -Steve

You do realize that you have used "s" in the D version?
This works as expected:

writefln("%0.3f", f); // 20.667
printf("%0.3f\n", f); // 20.667

This is a bit more interesting:

writefln("%0.3s", f); // 20.7
printf("%0.3s\n", f); // 20.