注解：
ANSI 'American Standard Code for Information Interchange' 美国信息互换标准代码 ANSI的'Ascii'编码
Unicode 'Universal Multiple-Octet Coded Character Set' 简称 UCS, 俗称 'Unicode'
UTF 'UCS Transfer Format'
DBCS 'Double Byte Charecter Set' 双字节字符集
相关重要函数过程:
WinAPI:
MultiByteToWideChar WideCharToMultiByte
相关参数(CodePage)
CP_ACP ANSI code page
CP_MACCP Not supported
CP_OEMCP OEM code page
CP_SYMBOL Not supported
CP_THREAD_ACP Not supported
CP_UTF7 UTF-7 code page
CP_UTF8 UTF-8 code page
单元System.pas:
function StringToWideChar(const Source: string; Dest: PWideChar; DestSize: Integer): PWideChar;
function WideCharToString(Source: PWideChar): string;
function WideCharLenToString(Source: PWideChar; SourceLen: Integer): string;
procedure WideCharToStrVar(Source: PWideChar; var Dest: string);
procedure WideCharLenToStrVar(Source: PWideChar; SourceLen: Integer; var Dest: string);
type
UCS2Char = WideChar; PUCS2Char = PWideChar;
UCS4Char = type LongWord;
UCS4String = array of UCS4Char;
function PUCS4Chars(const S: UCS4String): PUCS4Char;
function WideStringToUCS4String(const S: WideString): UCS4String;
function UCS4StringToWideString(const S: UCS4String): WideString;
function UnicodeToUtf8(Dest: PChar; Source: PWideChar; MaxBytes: Integer): Integer; overload; deprecated;
function Utf8ToUnicode(Dest: PWideChar; Source: PChar; MaxChars: Integer): Integer; overload; deprecated;
function UnicodeToUtf8(Dest: PChar; MaxDestBytes: Cardinal; Source: PWideChar; SourceChars: Cardinal): Cardinal; overload;
function Utf8ToUnicode(Dest: PWideChar; MaxDestChars: Cardinal; Source: PChar; SourceBytes: Cardinal): Cardinal; overload;
function UTF8Encode(const WS: WideString): UTF8String;
function UTF8Decode(const S: UTF8String): WideString;
function AnsiToUtf8(const S: string): UTF8String;
function Utf8ToAnsi(const S: UTF8String): string;