//江雪 2001.06.11  http://asnowcn.at.china.com

//将utf-8字符串转为代码页为codepage的ansistring。

function utf8toansistring(utf8str:string; codepage:integer):ansistring;

var

i:integer;

buffer:widestring;

ch,c1,c2:byte;

begin

result:='';

i:=1;

while i<=length(utf8str) do begin

  ch:=byte(utf8str[i]);

  setlength(buffer,length(buffer)+1);

  if (ch and $80)=0 then //1-byte

     buffer[length(buffer)]:=widechar(ch)

  else begin

  if (ch and $e0) = $c0 then begin // 2-byte

     inc(i);

     c1 := byte(utf8str[i]);

     buffer[length(buffer)]:=widechar((word(ch and $1f) shl 6) or (c1 and $3f));

   end

   else begin // 3-byte

     inc(i);

     c1 := byte(utf8str[i]);

     inc(i);

     c2 := byte(utf8str[i]);

     buffer[length(buffer)]:=widechar(

       (word(ch and $0f) shl 12) or

       (word(c1 and $3f) shl 6) or

       (c2 and $3f));

   end;

   end;

  inc(i);

 end; //while

 i := widechartomultibyte(codepage,

          wc_compositecheck or wc_discardns or wc_sepchars or wc_defaultchar,

          @buffer[1], -1, nil, 0, nil, nil);

 if i>1 then begin

   setlength(result, i-1);

   widechartomultibyte(codepage,

       wc_compositecheck or wc_discardns or wc_sepchars or wc_defaultchar,

       @buffer[1], -1, @result[1], i-1, nil, nil);

 end;

end;