关闭程序时出现错误,为什么?

Question

我在程序中定义了如下结构type
    PTThreadStruct = ^TThreadStruct;
    TThreadStruct = record
        MSendBuf            :Pointer;    
        MStream             :TMemoryStream;    
end;再定义如下动态数组
PRT_ThreadStruct    :array of PTThreadStruct;         在窗体打开后 
    setlength(PRT_ThreadStruct,2)
    For i:= 1 to   2 do
    begin               New(PRT_ThreadStruct[i]);
               GetMem(PRT_ThreadStruct[i].MSendBuf ,1024);
               PRT_ThreadStruct[i].MStream := TMemoryStream.Create ;    end;
在关闭窗体前我对动态组也做了释放,关闭程序时老是提示无效的指针操作
我将动态数组改为
PRT_ThreadStruct    :array[1..2] of PTThreadStruct;    
程序就不会报错了,请问是什么原因啊?答对马上揭帖

Answer 1

完整代码如下:procedure TForm1.Button1Click(Sender: TObject);
begin
    setlength(PRT_ThreadStruct,2)
    For i:= 1 to   2 do
    begin               New(PRT_ThreadStruct[i]);
               GetMem(PRT_ThreadStruct[i].MSendBuf ,1024);
               PRT_ThreadStruct[i].MStream := TMemoryStream.Create ;    end;end;
procedure TForm1.Button2Click(Sender: TObject);
begin
    For i:= 1 to   2 do
    begin
        freeMem(PRT_ThreadStruct[i].MSendBuf);
        PRT_ThreadStruct[i].MStream.free ;
        PRT_ThreadStruct[i].MStream:= nil;
        Dispose(PRT_ThreadStruct[1]);
        PRT_ThreadStruct[1] := nil;
    end;
end;
先单击button1,再单击button2,关闭程序,就会报错!
 zswangII(伴水清清)你去试试,谢谢了!

Answer 2

//是否声明顺序有问题？改如下试试，不行不要骂我丫。
type
    TThreadStruct = record
        MSendBuf            :Pointer;    
        MStream             :TMemoryStream;    
    end;
    PTThreadStruct = ^TThreadStruct;

Answer 3

button1中：For i:= low(PRT_ThreadStruct) to high(PRT_ThreadStruct) do
button2中：For i:=high(PRT_ThreadStruct) downto low(PRT_ThreadStruct) do

Answer 4

To : gwolf(阿呆)   确实不报错了,是啥原因啊?

Answer 5

我调试了一下:
button1中：For i:= low(PRT_ThreadStruct) to high(PRT_ThreadStruct) do 
实际是从0到1
button2中：For i:=high(PRT_ThreadStruct) downto low(PRT_ThreadStruct) do
是从1到0但是我如果将他们改为
for i:=1 to 2
就会报错,难道动态数组只能从0开始?

Answer 6

动态数组的下标问题，偶也一知半解，使用low()和high()是安全的方法