奇怪的问题：类里面的成员数组调用

Question

代码如下：
D7下编译通过，但在外部执行SentenceStarts的方法时出错
谁能帮我解决这个问题呀！unit RcEdit;interfaceuses
  Classes, ComCtrls;type
{TSentenceStarts}
  TSentenceStarts=class(TObject)
  private
    FSentenceStart:array of integer;
    FCount:integer;
    function GetStart(Index: integer):integer;
    procedure SetStart(Index, Value: integer);
  public
    constructor Create;
    destructor Destroy; override;
    procedure Add(Value:integer);
    property Count: integer read FCount;
    property SentenceStart[Index: integer]: integer read GetStart write SetStart; default;
  end;implementation{
****************************** TSentenceStarts *********************************
}
constructor TSentenceStarts.Create;
begin
  inherited Create;
  SetLength(FSentenceStart,100);
  FCount:=0;
end;destructor TSentenceStarts.Destroy;
begin
  inherited Destroy;
end;function TSentenceStarts.GetStart(Index: integer):integer;
begin
  if (Index>FCount-1) then
    Index:=High(FSentenceStart)+1;
  Result:=FSentenceStart[Index];
end;procedure TSentenceStarts.SetStart(Index, Value: integer);
begin
  if (Index>FCount-1) then
    Index:=High(FSentenceStart)+1;
  FSentenceStart[Index]:=Value;
end;procedure TSentenceStarts.Add(Value:integer);
begin
  FSentenceStart[FCount]:=Value;
  inc(FCount);
  if High(FSentenceStart)<FCount then
    SetLength(FSentenceStart,High(FSentenceStart)+6);
end;end.

Answer 1

Index:=High(FSentenceStart)+1;
  Result:=FSentenceStart[Index];//越界

Answer 2

Index:=High(FSentenceStart)+1;
  Result:=FSentenceStart[Index];//越界我觉得即使越界，程序也不该报错才对啊！只是程序并没有给FSentenceStart[Index]分配内存，应该会返回0吧！不过考虑点越界问题是好的，动态数组是从索引0开始的。
程序应该没什么问题！

Answer 3

不会越界High(FSentenceStart),经测试过的，因为下标是从零开始的

Answer 4

唉
创建：
  SetLength(FSentenceStart,100);
赋值
procedure TSentenceStarts.SetStart(Index, Value: integer);Index:=High(FSentenceStart)+1;/101
  Result:=FSentenceStart[101];//越界

Answer 5

赋值：  
  Index:=High(FSentenceStart)+1;//101
  Result:=FSentenceStart[Index];//越界

Answer 6

还是粘错了 
   Index:=High(FSentenceStart)+1;//101
  FSentenceStart[Index]:=Value;//越界不好意思：）

Answer 7

类初始化时候已经SetLength(FSentenceStart,100);分配内存空间
估计是数组越界!

Answer 8

"唉
创建：
  SetLength(FSentenceStart,100);
赋值
procedure TSentenceStarts.SetStart(Index, Value: integer);Index:=High(FSentenceStart)+1;/101"  //此处不为101而应该是100，High(FSentenceStart)＝99
动态数组 0～99