StrPCopy与StrPas功能正好相反，作用是与C语言字符串和Delphi的String相互转化

StrPCopy = Copies an AnsiString (long string) to a null-terminated string.
function StrPCopy(Dest: PAnsiChar; const Source: AnsiString): PAnsiChar; overload;

StrPas = Converts null-terminated string to an AnsiString (long string).
function StrPas(const Str: PAnsiChar): AnsiString; overload;

 

新版Delphi有两种重载：
function StrPas(const Str: PAnsiChar): AnsiString;
function StrPas(const Str: PWideChar): UnicodeString;
所以也可以是把指针转换为UnicodeString

所以StrPCopy也是如此：
function StrPCopy(Dest: PAnsiChar; const Source: AnsiString): PAnsiChar;
function StrPCopy(Dest: PWideChar; const Source: UnicodeString): PWideChar;

Pos更是有四种情况：
function Pos(const SubStr, Str: _ShortStr; Offset: Integer): Integer;
function Pos(const SubStr, Str: UnicodeString; Offset: Integer): Integer; overload;
function Pos(const SubStr, Str: _WideStr; Offset: Integer): Integer; overload;
function Pos(const SubStr, Str: _RawByteStr; Offset: Integer): Integer;