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February 13th, 2017, 06:36 AM
#1
Using CString into static method
I am stuck into a strange problem. I have MDI app, which has a struct into CDocument:
Code:
class CMyDoc : public CDocument
{
...
struct SRecord
{
SRecord(){}
virtual ~SRecord(){}
CString sName;
CString sState;
CString sDateu;
CString sDatec;
};
CTypedPtrArray<CPtrArray, SRecord*> m_arrRecord;
and somewhere in document I load this struct with data:
Code:
SRecord* pItem = new SRecord;
pItem->sName = saItem.GetAt(ML_ASSETNAME);
pItem->sState = saItem.GetAt(ML_STATE);
pItem->sDateu = saItem.GetAt(ML_DATEU;
pItem->sDatec = saItem.GetAt(ML_DATEC);
m_arrRecord.Add(pItem);
ok by now. I am trying to sort data:
Code:
void CMyDoc::SortData(int nColumn, BOOL bAscending)
{
switch(nColumn)
{
case 9:
if(bAscending)qsort((void*)m_arrRecord.GetData(), m_arrRecord.GetSize(), sizeof(SRecord), CompareDateUAscending);
else qsort((void*)m_arrRecord.GetData(), m_arrRecord.GetSize(), sizeof(SRecord), CompareDateUDescending);
break;
...
}
but the problem occur when data is access in static method:
Code:
//static method:
int CMyDoc::CompareDateUDescending(const void* arg1, const void* arg2)
{
SRecord* Record1 = *(SRecord**)arg1; // <-- OK
SRecord* Record2 = *(SRecord**)arg2; // <-- Unhandled exception* see note below
if(Record1->sDateu.IsEmpty() || Record2->sDateu.IsEmpty())
return 0;
COleDateTime dL, dR;
dL.ParseDateTime(Record1->sDateu);
dR.ParseDateTime(Record2->sDateu);
return (dL == dR ? 0 : (dL < dR ? 1 : -1));
}
*and the crash told me:
"An unhandled exception was encountered during a user callback."
What could be the problem ? Can you help me ? Thank you.
Last edited by mesajflaviu; February 13th, 2017 at 06:58 AM.
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February 13th, 2017, 08:03 AM
#2
Re: Using CString into static method
What is the value of arg2 when it is attempted to be dereferenced - and is it valid? If you single step through this code with the debugger what happens?
What is the type of m_arrRecord.GetData() ?
Assuming .GetData() returns a pointer to an array of SRecord, then shouldn't the code be ??
Code:
SRecord* Record1 = (SRecord*)arg1;
SRecord* Record2 = (SRecord*)arg2;
PS in light of ovidiucucu's post #3 stating that the elements of m_arrRecord are pointers to SRecord and not objects of SRecord, then my above assumption re what .Getdata() returns isn't right.
Last edited by 2kaud; February 13th, 2017 at 08:30 AM.
Reason: PS
All advice is offered in good faith only. All my code is tested (unless stated explicitly otherwise) with the latest version of Microsoft Visual Studio (using the supported features of the latest standard) and is offered as examples only - not as production quality. I cannot offer advice regarding any other c/c++ compiler/IDE or incompatibilities with VS. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/ and can be used without reference or acknowledgement. Also note that I only provide advice and guidance via the forums - and not via private messages!
C++23 Compiler: Microsoft VS2022 (17.6.5)
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February 13th, 2017, 08:10 AM
#3
Re: Using CString into static method
The elements of m_arrRecord are pointers and not objects of SRecord type.
So, you have to pass sizeof(SRecord*) and not sizeof(SRecord).
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February 13th, 2017, 08:27 AM
#4
Re: Using CString into static method
"What is the type of m_arrRecord.GetData() ?"
void**
"then shouldn't the code be ??"
I have already tried that, doesn't worked, crash the program here:
Code:
SRecord* Record1 = (SRecord*)arg1;
and led me here:
Code:
CStringData* GetData() const throw()
{
return( reinterpret_cast< CStringData* >( m_pszData )-1 ); // the crash lead me on this line
}
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February 13th, 2017, 08:28 AM
#5
Re: Using CString into static method
Originally Posted by ovidiucucu
The elements of m_arrRecord are pointers and not objects of SRecord type.
So, you have to pass sizeof(SRecord*) and not sizeof(SRecord).
Ovidiu, it works now !! Kindly thank you again !!!
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