What is the 'best practice' when converting from dchar to char or vice versa?  And wchar of course.

I expected this code to do a magic conversion:

dchar[] one = "one";
char[] one_a = cast(char[]) one;

Instead, it produces 'o...n...e...' where . is a 0 byte, in other words it casts the D type of the array but does not change the encoding.

I think this is not entirely unreasonable design, but, since implicit conversions don't work and explicit conversions do as shown above, there must be some standard way of going from one format to another, right?

I have this:

    dchar[] okay;
    foreach(ch; c) {
        okay ~= ch;
    }

Which seems to work fine, but seems a little piecemeal.  Is there a more standard idiomatic way to do this?

Kevin

// Code

import std.stdio;

void hexdump(T)(char[] z, T[] s)
{
    char[] pad = z.dup;
    pad[] = ' ';

    writefln("%s, %s * %s", z, s.length, T.sizeof);

    writef("%s --> ", z);
    byte * b = cast(byte*) s.ptr;
    int N = s.length*T.sizeof;

    for(int i = 0; i < N; i++) {
        writef("%2.2x ", b[i]);

        if ((i & 7) == 7)
            writef("\n %s    ", pad);
    }
    writefln("\n");
}

int main()
{
    char[]  c = "abcd";
    wchar[] w = "1234";
    dchar[] d = "WXYZ";

    dchar[] okay;
    foreach(ch; c) {
        okay ~= ch;
    }

    char[] okay2;
    foreach(ch; okay) {
        okay2 ~= ch;
    }

    hexdump("char", c);
    hexdump("wchar", w);
    hexdump("dchar", d);
    hexdump("okay-C", okay);
    hexdump("okay-D", okay2);

    char[] dc = cast(char[]) d;
    char[] wc = cast(char[]) w;
    dchar[] cd = cast(dchar[]) c;

    hexdump!(char) ("d-to-c", dc);
    hexdump!(char) ("w-to-c", wc);
    hexdump!(dchar)("c-to-d", cd);

    return 0;
}

// Output

char, 4 * 1
char --> 61 62 63 64

wchar, 4 * 2
wchar --> 31 00 32 00 33 00 34 00

dchar, 4 * 4
dchar --> 57 00 00 00 58 00 00 00
          59 00 00 00 5a 00 00 00

okay-C, 4 * 4
okay-C --> 61 00 00 00 62 00 00 00
           63 00 00 00 64 00 00 00

okay-D, 4 * 1
okay-D --> 61 62 63 64

d-to-c, 16 * 1
d-to-c --> 57 00 00 00 58 00 00 00
           59 00 00 00 5a 00 00 00

w-to-c, 8 * 1
w-to-c --> 31 00 32 00 33 00 34 00

c-to-d, 1 * 4
c-to-d --> 61 62 63 64

Kevin Bealer wrote:
> 
> What is the 'best practice' when converting from dchar to char or vice versa?  And wchar of course.

http://www.prowiki.org/wiki4d/wiki.cgi?CharsAndStrs

> I expected this code to do a magic conversion:
> 
> dchar[] one = "one";
> char[] one_a = cast(char[]) one;

No Magic in Phobos, sorry...

--anders

Kevin Bealer wrote:
> What is the 'best practice' when converting from dchar to char or vice versa?  And wchar of course.
> 
> I expected this code to do a magic conversion:
> 
> dchar[] one = "one";
> char[] one_a = cast(char[]) one;


import std.utf;
char[] one_a = toUTF8(one);

There's also toUTF16 and toUTF32.

Anders F Björklund wrote:
> Kevin Bealer wrote:
>>
>> What is the 'best practice' when converting from dchar to char or vice versa?  And wchar of course.
> 
> http://www.prowiki.org/wiki4d/wiki.cgi?CharsAndStrs
> 
>> I expected this code to do a magic conversion:
>>
>> dchar[] one = "one";
>> char[] one_a = cast(char[]) one;
> 
> No Magic in Phobos, sorry...
> 
> --anders

Thanks -- nice writeup btw.

Kevin