Reading a string in binary mode

[John Colvin]

On Monday, 3 March 2014 at 21:44:16 UTC, Christof Schardt wrote:
> I'm evaluating D and try to write a binary io class.
> I got stuck with strings:
>
>     void rw(ref string x)
>     {
>         if(_isWriting)
>         {
>             int size = x.length;
>             _f.rawWrite((&size)[0..1]);
>             _f.rawWrite(x);
>         }
>         else
>         {
>             int size;
>             _f.rawRead((&size)[0..1]);
>
>             ... what now?
>         }
>     }
>
> Writing is ok, but how do I read the bytes to the
> string x after having its size?


Assuming you're not expecting pre-allocation (which I infer from 
your choice of "ref string" instead of "char[]"), you could do 
this:

>     void rw(ref string x)
>     {
>         if(_isWriting)
>         {
>             size_t size = x.length;
>             _f.rawWrite((&size)[0..1]);
>             _f.rawWrite(x);
>         }
>         else
>         {
>             size_t size;
>             _f.rawRead((&size)[0..1]);
>             auto tmp = new char[size];
>             _f.rawRead(tmp);
>             import std.exception : assumeUnique;
>             x = tmp.assumeUnique;
>         }
>     }