On Monday, 24 September 2012 at 15:05:54 UTC, Jason Spencer wrote:
I imagine there's a slick way to do this, but I'm not seeing it.
I have a string of hex digits which I'd like to convert to an
array of 8 ubytes:
0123456789abcdef --> [0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD,
0xEF]
I'm looking at std.format.formattedRead, but the documentation
is...lightish. First of all, it seems there's no format
specifier except %s on reads and type information is gleaned
from the args' types. I was able to experiment and show that
%x works, but no documentation on exactly how.
Second, array syntax seems to work only if there's some
delimiter. With:
void main(string[] args)
{
ubyte[8] b;
formattedRead(args[1], "%(%s%)", &b);
}
I get
std.conv.ConvOverflowException@C:\Tools\D\dmd2\windows\bin\..\..\src\phobos\std\
conv.d(2006): Overflow in integral conversion
at least once. :) But that makes sense--hard to tell how many
input chars to assign to one byte versus another (although it
seems to me a hungry algorithm would work--saturate one type's
max and move to the next.)
There doesn't seem to be any support for field sizes or counts
in formatted read, similar to old C "%16x". This barks at me
right away--"%1 not supported."
I know I could read (in this case) as two longs or a uint16,
but I don't want to deal with endianess--just data.
Is there some trick to use the fact that b is fixed size 8
bytes and know that requires 16 hex digits and converts
automatically? Is there some other suggestion for how to do
this eloquently? I can play around with split and join, but it
seemed like there is probably some way to do this directly that
I'm not seeing.
Thanks!
Jason
I think that you are not supposed to use a static array: If there
are not EXACTLY as many array elements as there are parse-able
elements, then the formatted read will consider the parse to have
failed.
Try this, it's what you want, right?
--------
void main()
{
string s = "ffff fff ff f";
ushort[] vals;
formattedRead(s, "%(%x %)", &vals);
writefln("%(%s - %)", vals);
}
--------
65535 - 4095 - 255 - 15
--------
Regarding the %1x, well, I guess it just isn't supported (yet?)
