Debug assertion thrown when trying to get values from XLRow, MSVC 2022, MFC

[rmmales]

Working in VS Community Edition 2022, I have successfully built OpenXLSX through CMake and DOxygen docs, run all demo programs as console apps.

I need to use OpenXLSX in an existing legacy MFC application. In Debug I can successfully open a workbook and worksheet and iterate through the rows and can view the contents of XLRow. However, as soon as I change the code to read the values in a row, a debug assertion is thrown.

Here is the code snippet:

void  CBeckyDlg::ReadExcelFile(const CString sExcelFileName)
{
	CString sTemp;
	XLDocument doc;
	// need to convert from CString to std::string
	std::string s((LPCTSTR)sExcelFileName);
	doc.open(s);
	// open the worksheet note hard-wired name, need to fix
	auto wksDE = doc.workbook().worksheet("AllDEData_7_9_2023"); 

	int column_count = wksDE.columnCount();
	int row_count = wksDE.rowCount();
	// write the worksheet size to the output file
	sTemp.Format("Excel File %s Rows %d Columns %d\n", sExcelFileName, row_count, column_count);
	gOutputFile.WriteString(sTemp);
	gOutputFile.Flush();

	int rowcounter = 0;
	XLRow tempXLRow;
	std::list<XLCellValue> writeValues;
	// iterate through the first 10 rows of the worksheet
	for (auto& row : wksDE.rows()) {
		rowcounter++;
		tempXLRow = row;
		//writeValues = tempXLRow.values();  // PROBLEM HERE IF I UNCOMMENT
		if (rowcounter > 10)
			break;
		sTemp.Format("Excel Row %d\n", rowcounter);
		gOutputFile.WriteString(sTemp);
		gOutputFile.Flush();
		}
	doc.close();
	return;
}`


This code, when run with the writeValues=tempXLRow.values() line commented out, generates output as it should:

Excel File C:\ProgramData\Beachfx\Data\AllDEData_7_9_2023.xlsx Rows 1075 Columns 27
Excel Row 1
Excel Row 2
Excel Row 3
Excel Row 4
Excel Row 5
Excel Row 6
Excel Row 7
Excel Row 8
Excel Row 9
Excel Row 10

The error that is thrown is:
Program: C:\Projects\BeachFx\BeachFxCodeWorkingCopy\Debug\BeachFx.exe
File: minkernel\crts\ucrt\src\appcrt\heap\debug_heap.cpp
Line: 996

Expression: __acrt_first_block == header

For information on how your program can cause an assertion
failure, see the Visual C++ documentation on asserts.

(Press Retry to debug the application)
The thread 0x1488 has exited with code 0 (0x0).
The thread 0x3a94 has exited with code 0 (0x0).
The thread 0x60c has exited with code 0 (0x0).
A breakpoint instruction (__debugbreak() statement or a similar call) was executed in BeachFx.exe.

Debug Assertion Failed!

Program: C:\Projects\BeachFx\BeachFxCodeWorkingCopy\Debug\BeachFx.exe
File: minkernel\crts\ucrt\src\appcrt\heap\debug_heap.cpp
Line: 996

Expression: __acrt_first_block == header

I just need a workaround so that I can extract the non-homogeneous row data (columns are variously numbers, strings, dates) from the returned std::list.

Note that I have tried various attempts from the demo examples, the above code snippet is the simplest I have found that allows the needed iteration through the rows.

[CEXT-Dan]

I’m also running this code inside a MFC app, with no issues.
Could it be compiler settings?
https://learn.microsoft.com/en-us/answers/questions/240332/assert-when-using-mtd-dynamic-library

[rmmales]

Thank you for this suggestion. I am still trying to work through it, not there yet.

Do you know if it is also necessary to modify the build of OpenXLSX through CMake for debug? I am building as a static library, would this be better as a shared library?

[CEXT-Dan]

it’s been some time, I used visual studio cmake tools to generate CMakeSettings.json. for debug and release
I am also using a static library, which I think it’s better because of whole program optimization