Delphi编码转换

1、Delphi 的 Utf-8 转换 - findumars - 博客园.html

https://www.cnblogs.com/findumars/archive/2013/12/26/3492891.html

新版的 Delphi 應該不用這麼麻煩, 據說只要直接在 AnsiString, WideString, UTF8String 之間 assign 時就會自動幫你做轉換 (沒用過, 不知道是不是真的這樣就可以).

不過... 還在用 Delphi 3/5, 所以... 只好自己來轉:

unit util_utf8;
 
interface
 
uses Windows;
 
type
  UTF8String = AnsiString;
 
  function AnsiToWide(const S: AnsiString): WideString;
  function WideToUTF8(const WS: WideString): UTF8String;
  function AnsiToUTF8(const S: AnsiString): UTF8String;
  function UTF8ToWide(const US: UTF8String): WideString;
  function WideToAnsi(const WS: WideString): AnsiString;
  function UTF8ToAnsi(const S: UTF8String): AnsiString;
 
implementation
 
function AnsiToWide(const S: AnsiString): WideString;
var len: integer;
    ws: WideString;
begin
Result:='';
if (Length(S) = 0) then
  exit;
len:=MultiByteToWideChar(CP_ACP, 0, PChar(s), -1, nil, 0);
SetLength(ws, len);
MultiByteToWideChar(CP_ACP, 0, PChar(s), -1, PWideChar(ws), len);
Result:=ws;
end;
 
function WideToUTF8(const WS: WideString): UTF8String;
var len: integer;
    us: UTF8String;
begin
Result:='';
if (Length(WS) = 0) then
  exit;
len:=WideCharToMultiByte(CP_UTF8, 0, PWideChar(WS), -1, nil, 0, nil, nil);
SetLength(us, len);
WideCharToMultiByte(CP_UTF8, 0, PWideChar(WS), -1, PChar(us), len, nil, nil);
Result:=us;
end;
 
function AnsiToUTF8(const S: AnsiString): UTF8String;
begin
Result:=WideToUTF8(AnsiToWide(S));
end;
 
function UTF8ToWide(const US: UTF8String): WideString;
var len: integer;
    ws: WideString;
begin
Result:='';
if (Length(US) = 0) then
  exit;
len:=MultiByteToWideChar(CP_UTF8, 0, PChar(US), -1, nil, 0);
SetLength(ws, len);
MultiByteToWideChar(CP_UTF8, 0, PChar(US), -1, PWideChar(ws), len);
Result:=ws;
end;
 
function WideToAnsi(const WS: WideString): AnsiString;
var len: integer;
    s: AnsiString;
begin
Result:='';
if (Length(WS) = 0) then
  exit;
len:=WideCharToMultiByte(CP_ACP, 0, PWideChar(WS), -1, nil, 0, nil, nil);
SetLength(s, len);
WideCharToMultiByte(CP_ACP, 0, PWideChar(WS), -1, PChar(s), len, nil, nil);
Result:=s;
end;
 
function UTF8ToAnsi(const S: UTF8String): AnsiString;
begin
Result:=WideToAnsi(UTF8ToWide(S));
end;
 
end.

就是直接使用 win32 的 API 來處理.
PS. 舊的 VCL 只支援 Ansi, 所以... WideString 與 UTF8String (定義與 AnsiString 相同) 並沒有辦法正確的在 VCL 中顯示.

原文：http://blog.teatime.com.tw/1/post/419

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