I got some excel files, I need to read data from it and upload data to some database (I need to use firebird, but whatever). Right now I use <QAxObject> from Qt and code look like

QAxObject* excel = new QAxObject("Excel.Application"); //pointer to excel 
//excel->setProperty("Visible", false); 
QAxObject* workbooks = excel->querySubObject("WorkBooks"); //get pointer to booklist
workbooks->dynamicCall("Open (const QString&)", QString("C:\\databases\\test.xls")); //opening file, getting pointer to booklist
QAxObject* workbook = excel->querySubObject("ActiveWorkBook"); 
QAxObject* worksheets = workbook->querySubObject("WorkSheets"); 

etc.

The problem is that this way on users PC there must be installed Excel.

Is there exists some free C++ libraries to work with *.xls, *.xlsx files without Excel installed?