delphi pansichar 转pwidechar

const
a: PAnsiChar = ‘a23中’;
var
b,c: pchar;
begin
GetMem(b,4);
FillMemory(b,SizeOf(b)*4,0);
StrCopy((b),PWideChar((a)));
// CopyMemory(b,(a),Length(a));

ShowMessage(PAnsiChar(b));
c := PChar(a);
ShowMessage(PAnsiChar(c));
ShowMessage(a);
FreeMem(b);