On 03/31/2012 08:56 AM, Jacob Carlborg wrote:
> How would I read a unicode character from the terminal? I've tried using
> "std.cstream.din.getc"
I recommend using stdin. The destiny of std.cstream is uncertain and
stdin is sufficient. (I know that it lacks support for BOM but I don't
need them.)
> but it seems to only work for ascii characters.
> If I try to read and print something that isn't ascii, it just prints a
> question mark.
The word 'character' used to mean characters of the Latin-based
alphabets but with Unicode support that's not the case anymore. In D,
'character' means UTF code unit, nothing else. Unfortunately, although
'Unidode character' is just the correct term to use, it conflicts with
D's characters which are not Unicode characters.
'Unicode code point' is the non-conflicting term that matches what we
mean with 'Unicode character.' Only dchar can hold code points.
That's the part about characters.
The other side is what is being fed into the program through its
standard input. On my Linux consoles, the text comes as a stream of
chars, i.e. a UTF-8 encoded text. You must ensure that your terminal is
capable of supporting Unicode through its settings. On Windows
terminals, one must enter 'chcp 65001' to set the terminal to UTF-8.
Then, it is the program that must know what the data represents. If you
are expecting a Unicode code point, then you may think that is should be
as simple as reading into a dchar:
import std.stdio;
void main()
{
dchar letter;
readf("%s", &letter); // <-- does not work!
writeln(letter);
}
The output:
$ ./deneme
ç
à <-- will be different on different consoles
The problem is, char can implicitly be converted to dchar. Since the
letter ç consists of two chars (two UTF-8 code units), dchar gets the
first one converted as a dchar.
To see this, read and write two chars in a loop without a newline in
between:
import std.stdio;
void main()
{
foreach (i; 0 .. 2) {
char code;
readf("%s", &code);
write(code);
}
writeln();
}
This time two code units are read and then outputted to form a Unicode
character on the console:
$ ./deneme
ç
ç <-- result of two write(code) expressions
The solution is to use ranges when pulling Unicode characters out of
strings. std.stdin does not provide this yet, but it will eventually
happen (so I've heard :)).
For now, this is a way of getting Unicode characters from the input:
import std.stdio;
void main()
{
string line = readln();
foreach (dchar c; line) {
writeln(c);
}
}
Once you have the input as a string, std.utf.decode can also be used.
Ali
