conver BigInt to string

[BBasile via Digitalmars-d-learn]

On Thursday, 5 November 2015 at 16:29:30 UTC, Namal wrote:
> Hello I am trying to convert BigInt to string like that while 
> trying to sort it:
>
> string s1 = to!string(a).dup.sort;
>
> and get an error
>
> cannot implicitly convert expression (_adSortChar(dup(to(a)))) 
> of type char[] to string
>
> what do I do wrong?

try

".idup"

otherwise

"auto s1 = "