digitalmars.D.learn - XOR a bunch of data
- Tiago Gasiba <tiago.gasiba gmail.com> Oct 17 2005
- "Charles" <noone nowhere.com> Oct 17 2005
- Dave Akers <dragon dazoe.net> Jul 08 2008
- "Koroskin Denis" <2korden gmail.com> Jul 09 2008
Hi all,
Why can't I do the following?
--- code ---
import std.c.stdio;
import std.c.stdlib;
int main( ){
ulong[10] X, Y;
X[] = 2;
Y[] = 5;
X[] ^= Y[];
foreach( ulong u; X )
printf("%lu\n",u);
return 0;
}
--- code ---
The compiler complains:
test.d(8): slice expression X[] is not a modifiable lvalue
test.d(8): 'X[]' is not a scalar, it is a ulong[]
test.d(8): 'X[]' is not of integral type, it is a ulong[]
test.d(8): 'Y[]' is not of integral type, it is a ulong[]
What I want to do is simply this:
for( int ii=0; ii<X.length; ii++ )
X[ii] ^= Y[ii];
Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ???
Thanks!
Best,
Tiago Gasiba
--
Tiago Gasiba (MSc.) - http://www.gasiba.de
Everything should be made as simple as possible, but not simpler.
Oct 17 2005
Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ??? Thanks!
Not yet, those are whats been dubbed 'array arithematic operations' , and I think are planned for 2.0 ( hopefully sooner , can't really call them first-class arrays w/o em! ). It would probably look like : X ^= Y ; Thanks, Charlie "Tiago Gasiba" <tiago.gasiba gmail.com> wrote in message news:dj0e3m$cku$1 digitaldaemon.com...Hi all, Why can't I do the following? --- code --- import std.c.stdio; import std.c.stdlib; int main( ){ ulong[10] X, Y; X[] = 2; Y[] = 5; X[] ^= Y[]; foreach( ulong u; X ) printf("%lu\n",u); return 0; } --- code --- The compiler complains: test.d(8): slice expression X[] is not a modifiable lvalue test.d(8): 'X[]' is not a scalar, it is a ulong[] test.d(8): 'X[]' is not of integral type, it is a ulong[] test.d(8): 'Y[]' is not of integral type, it is a ulong[] What I want to do is simply this: for( int ii=0; ii<X.length; ii++ ) X[ii] ^= Y[ii]; Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ??? Thanks! Best, Tiago Gasiba -- Tiago Gasiba (MSc.) - http://www.gasiba.de Everything should be made as simple as possible, but not simpler.
Oct 17 2005
Dave Akers <dragon dazoe.net> Charles wrote:Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ??? Thanks!
Not yet, those are whats been dubbed 'array arithematic operations' , and I think are planned for 2.0 ( hopefully sooner , can't really call them first-class arrays w/o em! ). It would probably look like : X ^= Y ; Thanks, Charlie
Any idea how this will be implemented? something like ArrayXor(ubyte[] X, ubyte[] Y) { for (int i=0; i<X.length; i++) { X[i] ^= Y[i % Y.length]; } }"Tiago Gasiba" <tiago.gasiba gmail.com> wrote in message news:dj0e3m$cku$1 digitaldaemon.com...Hi all, Why can't I do the following? --- code --- import std.c.stdio; import std.c.stdlib; int main( ){ ulong[10] X, Y; X[] = 2; Y[] = 5; X[] ^= Y[]; foreach( ulong u; X ) printf("%lu\n",u); return 0; } --- code --- The compiler complains: test.d(8): slice expression X[] is not a modifiable lvalue test.d(8): 'X[]' is not a scalar, it is a ulong[] test.d(8): 'X[]' is not of integral type, it is a ulong[] test.d(8): 'Y[]' is not of integral type, it is a ulong[] What I want to do is simply this: for( int ii=0; ii<X.length; ii++ ) X[ii] ^= Y[ii];
what if Y.length < X.length... array bounds error...Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ??? Thanks! Best, Tiago Gasiba -- Tiago Gasiba (MSc.) - http://www.gasiba.de Everything should be made as simple as possible, but not simpler.
Jul 08 2008
On Wed, 09 Jul 2008 02:43:12 +0400, Dave Akers <dragon dazoe.net> wrote:Charles wrote:Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ??? Thanks!
and I think are planned for 2.0 ( hopefully sooner , can't really call them first-class arrays w/o em! ). It would probably look like : X ^= Y ; Thanks, Charlie
Any idea how this will be implemented? something like ArrayXor(ubyte[] X, ubyte[] Y) { for (int i=0; i<X.length; i++) { X[i] ^= Y[i % Y.length]; } }"Tiago Gasiba" <tiago.gasiba gmail.com> wrote in message news:dj0e3m$cku$1 digitaldaemon.com...Hi all, Why can't I do the following? --- code --- import std.c.stdio; import std.c.stdlib; int main( ){ ulong[10] X, Y; X[] = 2; Y[] = 5; X[] ^= Y[]; foreach( ulong u; X ) printf("%lu\n",u); return 0; } --- code --- The compiler complains: test.d(8): slice expression X[] is not a modifiable lvalue test.d(8): 'X[]' is not a scalar, it is a ulong[] test.d(8): 'X[]' is not of integral type, it is a ulong[] test.d(8): 'Y[]' is not of integral type, it is a ulong[] What I want to do is simply this: for( int ii=0; ii<X.length; ii++ ) X[ii] ^= Y[ii];
what if Y.length < X.length... array bounds error...Am I not allowed to XOR a bunch of data like this X[] ^= Y[] ??? Thanks! Best, Tiago Gasiba -- Tiago Gasiba (MSc.) - http://www.gasiba.de Everything should be made as simple as possible, but not simpler.
An exception will be thrown, I think: BTW, operation may be done faster if 4 bytes is xored per step (or even 8-bytes per step on x64): int* dst = cast(int*)X.ptr; int* src = cast(int*)Y.ptr; // xor int steps = X.length / X[0].sizeof; for (int i = steps; i >= 0; --i, ++src, ++dst) { *dst ^= *src; } // xor remaining byte-per-byte, code skipped.
Jul 09 2008