Delphi calls WINAPI characters and String functions: Chartooem, Oemtochar

The difference between Chartooembuff, Oemtocharbuff and Chartooem and Oemtochar is that the former can specify the number of characters to convert. unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls;
type
　TForm1 = class(TForm)
　　Button1: TButton;
　　Button2: TButton;
　　Button3: TButton;
　　Button4: TButton;
　　procedure Button1Click(Sender: TObject);
　　procedure Button2Click(Sender: TObject);
　　procedure Button4Click(Sender: TObject);
　　procedure Button3Click(Sender: TObject);
　end; Var

　Form1: TForm1;
implementation
{$R *.dfm}Procedure Tform1.button1click (Sender:tobject);var
　Buf: PWideChar;
　AnsiBuf: array[0..255] of AnsiChar;
begin
　Buf := '万一的 Delphi 博客';
　CharToOem(Buf, AnsiBuf);
　ShowMessage(string(AnsiBuf)); {万一的 Delphi 博客}
　FillChar(AnsiBuf, Length(AnsiBuf), #0);
　CharToOemBuff(Buf, AnsiBuf, 6);
　ShowMessage(string(AnsiBuf)); {万一的 De}
end;Procedure Tform1.button2click (Sender:tobject);var
　str: string;
　p: PAnsiChar;
begin
　str := '万一的 Delphi 博客';
　p := GetMemory(256);
　CharToOem(PChar(str), p);
　ShowMessage(string(p)); {万一的 Delphi 博客}
　FreeMemory(p);
　p := GetMemory(256);
　CharToOemBuff(PChar(str), p, 6);
　ShowMessage(string(p)); {万一的 De}
　FreeMemory(p);
end;Procedure Tform1.button3click (Sender:tobject);var
　AnsiBuf: PAnsiChar;
　Buf: array[0..255] of Char;
begin
　AnsiBuf := '万一的 Delphi 博客';
　OemToChar(AnsiBuf, buf);
　ShowMessage(string(Buf)); {万一的 Delphi 博客}
　FillChar(Buf, Length(Buf), #0);
　OemToCharBuff(AnsiBuf, buf, 6);
　ShowMessage(string(Buf)); {万一的}
end;Procedure Tform1.button4click (Sender:tobject);var
　AnsiStr: AnsiString;
　p: PChar;
begin
　AnsiStr := '万一的 Delphi 博客';
　p := StrAlloc(256);
　OemToChar(PAnsiChar(AnsiStr), p);
　ShowMessage(string(p)); {万一的 Delphi 博客}
　StrDispose(p);
　p := StrAlloc(256);
　OemToCharBuff(PAnsiChar(AnsiStr), p, 6);
　ShowMessage(string(p)); {万一的}
　StrDispose(p);
end;
end.