Floating point to string

[Joe]

Derek Parnell wrote:
> On Wed, 18 Jul 2007 21:28:47 -0500, Joe wrote:
> 
>> How to do get a full string representation of a floating point?
>>
>> I've tried toString() on a floating point and the default precision for 
>> numbers after the decimal point is 6.  I've also tried using format 
>> strings, but I can't seem to get a full textual representation of a 
>> floating point.  Is there some trick I'm missing?
> 
> Try this ...
> <dcode>
> import std.stdio;
> import std.string;
> 
> string FullTextValue(T)(T x)
> {
>     string s;
> 
>     static if(is (T:long))
>         const fmt = "%-52d";
>     else
>     static if(is (T:real))
>         const fmt = "%52.52f";
>     else
>         const fmt = "%-s";
> 
>     s = std.string.format( fmt, x);
>     for (int i = s.length-1; i >= 0; i--)
>     {
>         if (s[i] == '.')
>         {
>             s.length = i+2;
>             break;
>         }
>         if ((s[i] != '0' && s[i] != ' ') || (i == 0))
>         {
>             s.length = i+1;
>             break;
>         }
>     }
>     return s;
> }
> void main()
> {
>     real x;
>     double y;
>     float z;
>     long a;
> 
>     x = 12345678901234567890.1234567890123456789;
>     y = x;
>     z = x;
>     a = cast(typeof(a))x;
> 
>     writefln("real   '%s'", FullTextValue(x));
>     writefln("double '%s'", FullTextValue(y));
>     writefln("float  '%s'", FullTextValue(z));
>     writefln("long   '%s'", FullTextValue(a));
> 
>     x = 0.1234567890123456789;
>     y = x;
>     z = x;
>     a = cast(typeof(a))x;
> 
>     writefln("real   '%s'", FullTextValue(x));
>     writefln("double '%s'", FullTextValue(y));
>     writefln("float  '%s'", FullTextValue(z));
>     writefln("long   '%s'", FullTextValue(a));
> 
> }
> </dcode>
> 

Thanks.

Out of curiosity (note: I haven't run this example yet), is 52 a magic 
number for the floating point types in D?  Is there a way at runtime to 
get at the number of digits available after the decimal point depending 
on whether it's a float, double or real?