how to handle excel files using C++? - c++

Question

I'm new to C++, And I want to enter values into an excel spreadsheet using C++, I know we can handle files using fstream but how to get a specific column or row using this method.

Answer 1

If you want to persist in using C++ (despite the comments above), this sample will give you an idea of the coding work needed to use C++ to automate the Excel application (as you might do in VBA or C#) rather than manipulate the file using a known file format (using a third-party library). The sample opens an existing worksheet in the background, adds 1 to the value in cell A1 on Sheet1, and then saves it.
Whether this is a suitable or efficient solution for your case will depend on what exactly you are trying to do with the files.
NB. Only works with the MS Visual Studio compiler.
The hard-coded paths to the import libraries may be different on your computer, and may depend on your Excel version.
//Import all the type libraries
#import "C:\Program Files\Microsoft Office\Root\VFS\ProgramFilesCommonX86\Microsoft Shared\OFFICE16\MSO.dll" \
rename("RGB","RGB_mso") rename("DocumentProperties","DocumentProperties_mso")
using namespace Office;
#import "C:\Program Files\Microsoft Office\root\vfs\ProgramFilesCommonX86\Microsoft Shared\VBA\VBA6\VBE6EXT.OLB"
using namespace VBIDE;
#import "C:\Program Files\Microsoft Office\root\Office16\EXCEL.EXE" \
rename( "DialogBox", "ExcelDialogBox" ) \
rename( "RGB", "ExcelRGB" ) \
rename( "CopyFile", "ExcelCopyFile" ) \
rename( "ReplaceText", "ExcelReplaceText" ) \
exclude( "IFont", "IPicture" )
#include <iostream>
using namespace std;
int main()
{
HRESULT hr = CoInitializeEx(0, COINIT_MULTITHREADED);
Excel::_ApplicationPtr pXL;
if (FAILED(pXL.CreateInstance("Excel.Application")))
{
cout << "Could not create instance of Excel" << endl;
return 1;
}
try
{
//Uncomment this to see what is going on during each step
//pXL->Visible = true;
Excel::_WorkbookPtr pWb = pXL->Workbooks->Open(L"c:\\temp\\testbook.xlsx");
//Gets number from cell A1 in Sheet1 and increments
Excel::_WorksheetPtr pSheet = pWb->Worksheets->Item[L"Sheet1"];
Excel::RangePtr pRng = pSheet->Cells;
_variant_t val = pRng->Item[1][1];
double dVal{ val };
pRng->Item[1][1] = ++dVal;
pWb->Save();
pWb->Close();
}
catch (_com_error ce)
{
cout << "Something went wrong" << endl;
_bstr_t bstrDesc = ce.Description();
if( ! bstrDesc )
{
cout << " Unknown Error" << endl;
}
else
{
cout << " Error text: " << bstrDesc << endl;
}
}
pXL->Quit();
}
EDIT: In answer to the unspoken question why is it Excel::_ApplicationPtr, Excel::_WorkbookPtr etc, but for a Range it is Excel::RangePtr (no _)? Absolutely no idea.

Answer 2

C++ is probably no the best choice to use if you want to manipulate .xlsx files. You would be better off either using macros in Excel using VBA, or you can write an Excel plugin using VSTO. If you really need to stick with C++, consider if you really need native Excel format. Maybe just .csv file be sufficient.

Answer 3

OpenXLSX is a great library for reading and writing excel sheets using C++. Its API documentation is not in the Github repo. It can be found here. The examples in the repo are quite extensive and detailed. Build instructions are also straightforward.
I have tried it on Linux and Windows (with MinGW). It works great and has the same behavior on both OSs.