On Monday, 24 September 2012 at 22:38:59 UTC, Jason Spencer wrote:
On Monday, 24 September 2012 at 16:32:45 UTC, monarch_dodra
wrote:
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]
<snip>
void main(string[] args)
{
ubyte[8] b;
formattedRead(args[1], "%(%s%)", &b);
}
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.
The sample code was just for testing convenience. In practice
the string will be conditioned and known to have 16 characters
in {0-9, a-f}.
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);
}
Not quite. You've taken the liberty of using a
delimiter--spaces. I have to take 16 contiguous, NON-delimited
hex digits and produce 8 bytes. So I could read it as a uint64
(not uint16, as I mistakenly posted before), but then I'd have
to byte-reverse it. I could use slicing and do a byte at a
time. I just wondered if there were a slick way to get
in-place data from a contiguous hex string.
Thanks,
Jason
I am unsure if the non-support of %2x is by design, or just "not
yet supported".
Keep in mind that slicing a string *is* inplace. It is equivalent
to pointer arithmetic. I'd just do a loop:
--------
void main()
{
string s = "0123456789abcdef";
ushort[8] vals;
foreach(size_t i; 0..8)
{
string slice = s[2*i .. 2*(i+1)];
slice.formattedRead("%x", &vals[i]);
}
writeln(vals);
}
--------
[1, 35, 69, 103, 137, 171, 205, 239]
--------
Will still get the job done pretty cleanly and efficiently.
Chances are this is even faster and more efficient than a
supposed "%(%2x%)" scheme, since you are lowering the complexity
from a list of reads to a simple extract data.
Alternatively, you could just use conv's "to" or "parse". I've
had others argue that "ForamttedRead" is meant as an
implementation detail, and should be used by other functions, but
"consumers" shouldn't use it directly.
I found this strange at first, but I've grown fond of the power
of "to":
--------
import std.conv, std.stdio;
void main()
{
string s = "0123456789abcdef";
ushort[8] vals;
foreach(size_t i; 0..8)
vals[i] = s[2*i .. 2*(i+1)].to!ushort(16);
writeln(vals);
}
--------
Pretty nice, no?
