WinAPI:GetUserName-獲取當前用戶名

//聲明:
    GetUserName(
    lpBuffer: PChar;　{緩沖區(qū)}
    var nSize: DWORD　{緩沖區(qū)大小}
    ): BOOL;
    //舉例:
    var
    arr: array[0..254] of Char;
    d: DWORD;
    begin
    d := SizeOf(arr);
    GetUserName(arr, d);
    ShowMessage(arr);　 {wy}
    end;
    //另一例:
    var
    p: PChar;
    num: DWORD;
    begin
    num := 0;
    GetUserName(nil, num);
    ShowMessage(IntToStr(num));
    GetMem(p, num);
    GetUserName(p, num);
    ShowMessage(p);　　 {wy}
    FreeMem(p);
    end;
    //再一例:
    var
    p: PChar;
    num: DWORD;
    begin
    num := 0;
    GetUserName(nil, num);
    p := StrAlloc(num);
    if GetUserName(p,num) then
    ShowMessage(p)　　　　　{wy}
    else ShowMessage('無');
    StrDispose(p);
    end;