Re: Using vector as class member lead to Data Abort error
On 2=D4 20=C8=D5, =C9=CF=CE=E72=CA=B107=B7=D6, Joseph M. Newcomer <newco.=
...@flounder.com> wrote:
On Wed, 18 Feb 2009 17:34:01 -0800 (PST), "Jason .Y" <lin.yang.ja...@gmai=
l.com> wrote:
Hi, I'm coding on windows mobile 6 and I have meet a strange problem,
which I have already tried to Google it, but still cann't work it out.
here is my problem:
there is a class with avectoras member as below:
code:
/**********MyTest.h****************/
#pragma once
#include <string>
#include <vector>
class CMyTest
{
public:
CMyTest(void);
public:
~CMyTest(void);
private:
vector<string> m_vecString;
****
Be very, very careful about the use of 'private' and 'protected'. 'priva=
te' has a lot
more semantics than just "not-public" (see note below)
****
};
/*****************************/
and I also have a dialog class as below,which has CMyTest class
object:
/**************Mobile_Test**************/
// Mobile_TestDlg.h
#pragma once
#include <iostream>
#include <fstream>
#include "InfoDlg.h"
#include "MyTest.h"
#define WM_MSGWHITSTR (WM_USER+193)
****
You should not be using WM_USER-based symbols here, and you should NEVER =
name a
user-defined message as "WM_" anything because WM_ is reserved for Micros=
oft (the number
of times people have wasted hours trying to find a user-defined message i=
n the MSDN
documentation is amazing!) Use WM_APP-based or Registered Window Message=
s, and use a
prefix other than WM_ for your own messages.
****
class CMobile_TestDlg : public CDialog
{
public:
CMobile_TestDlg(CWnd* pParent = NULL);
enum { IDD = IDD_MOBILE_TEST_DIALOG };
protected:
virtual void DoDataExchange(CDataExchange* pDX);
protected:
HICON m_hIcon;
virtual BOOL OnInitDialog();
#if defined(_DEVICE_RESOLUTION_AWARE) && !defined
(WIN32_PLATFORM_WFSP)
afx_msg void OnSize(UINT /*nType*/, int /*cx*/, int /*cy*/);
#endif
DECLARE_MESSAGE_MAP()
/*================Data====
=================*/
public:
BYTE m_sharedDataArray[521];
private:
CMyTest m_test; //!!!!
****
Did you really mean "private" (as in, "I deliberately choose to not allow=
subclasses to
inherit") or "private" (as in, I mean, "not public, and should have said =
'protected'
instead")?
****
public:
static UINT Reader(LPVOID pParam);
static UINT Writer(LPVOID pParam);
public:
afx_msg void OnBnClickedButtonOk();
LRESULT OnMsgwithStr(WPARAM wParam, LPARAM lParam);
public:
afx_msg void OnBnClickedButtonTest();
};
/****************************/
this program compiled fine, but when I run it on Debug mode, I get
error as below:
Platform Type : PocketPC
DataAbort: Thread=97b0aa40 Proc=8c3e89e0 'Mobile_Test.exe'
AKY=00400001 PC=00018c38(Mobile_Test.exe+0x00008c38) RA=0001981c
(Mobile_Test.exe+0x0000981c) BVA=2e29f8f9 FSR=00000001
Unhandled exception at 0x00018c38 in Mobile_Test.exe: 0x80000002:
Datatype misalignment.
and this error seems to happen in the constructor of CTest. because
when I run it step by step, it turns out the error is happened at :
/************xutility.h*******************/
__CLR_OR_THIS_CALL _Container_base()
: _Myfirstiter(0)
{ // construct childless container
}
/****************************/
****
Well, it is looking like adataalignment problem. What are the variables =
in question?
What is the value of 'this', for example? You didn't give anything useful=
here. Note that
most Pocket PC architectures are RISC architectures, and this means they =
really, really
care aboutdataalignment. You have a weird size in your class, [521], whi=
ch seems to be
a random number. However, if you had your packing set incorrectly, then =
there is no
padding that follows and the next value will be misaligned. Irrelevant o=
n an x86,
critical on a RISC machine.
I don't know what a BVA is, but it is 9, and that looks odd. And that's =
both 'odd' as in
"not a multiple of 2" and odd as in "it is unusual to see an address on a=
RISC machine
that is not a multiple of 2, 4 or 8". If you changed the random number 5=
21 to 522 or 524,
does the problem go away?
The fact that it compiles does not guarantee its correctness.
joe
***
I have no idea why this error happened, Any assistance would be
appreciated.
Thx
Joseph M. Newcomer [MVP]
email: newco...@flounder.com
Web:http://www.flounder.com
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Than you very much