On Friday, 6 February 2015 at 17:09:29 UTC, Charles wrote:
I'm trying to create a template function that can take in any
type of array and convert it to a ubyte array. I'm not
concerned with endianness at the moment, but I ran into a
roadblock when trying to do this with strings. It already works
with ints, chars, etc.
Here's the relevant test code:
module byteReader;
public import std.system : Endian;
ubyte[] toBytes(T)(T[] arr)
{
if (arr == null)
{
return null;
}
ubyte[] result = new ubyte[arr.length];
foreach (key, val; arr)
{
result[key] = cast(ubyte) val; // This is line 16
}
return result;
}
string readString(ubyte[] buffer, uint offset, uint length)
{
assert( buffer.length >= offset + length );
char[] chars = new char[length];
foreach(key, val; buffer[offset .. offset + length])
{
chars[key] = cast(char) val;
}
return cast(string)chars;
}
void main() {
import std.stdio;
readString(toBytes!char(['t','e','s','t']),0,4).writeln;
readString(toBytes!string("test"),0,4).writeln; //
This is line 39
}
Here's the output:
byteReader.d(16): Error: cannot cast val of type string to
type ubyte
byteReader.d(39): Error: template instance
byteReader.toBytes!string error instantiating
Are you wanting to to convert each element in arr to a byte thus
truncating and losing data (when T.sizeof != 1)?
as in
toBytes([1,2,3, 42, 500 /*this will be truncated to 244
*/]);// T == int here
or are you wanting to convert each element to a ubyte array and
then concatenate it to the result.
as is
ubyte[] toBytes(T)(T[] arr)
{
ubyte[T.sizeof] buf;
if (arr is null)
{
return null;
}
ubyte[] result = new ubyte[arr.length * T.sizeof];
foreach (i, val; arr)
{
buf[] = cast(ubyte[T.sizeof])&(arr[i])[0 .. T.sizeof]
result ~= buf;
}
return result;
}
?
