How to protect Excel file with password in C++.NET

/*------------------------------------------------------------------------------
 | Tutorial 27
 |
 | This tutorial shows how to create an Excel file in C++.NET and
 | encrypt the Excel file by setting the password required for opening the file.
 -------------------------------------------------------------------------------*/

using namespace System;
using namespace EasyXLS;

int main()
{
    Console::WriteLine("Tutorial 27\n----------\n");

    // Create an instance of the class that exports Excel files, having two sheets
    ExcelDocument ^workbook = gcnew ExcelDocument(2);

    // Set the sheet names
    workbook->easy_getSheetAt(0)->setSheetName("First tab");
    workbook->easy_getSheetAt(1)->setSheetName("Second tab");

    // Set the password for protecting the Excel file when the file is open
    workbook->easy_getOptions()->setPasswordToOpen("password");

    // Export Excel file
    Console::WriteLine("Writing file C:\\Samples\\Tutorial27 - protect Excel with password and encryption.xlsx.");
    workbook->easy_WriteXLSXFile("C:\\Samples\\Tutorial27 - protect Excel with password and encryption.xlsx");

    // Confirm export of Excel file
    String ^sError = workbook->easy_getError();
    if (sError->Equals(""))
        Console::Write("\nFile successfully created. Press Enter to Exit...");
    else
        Console::Write(String::Concat("\nError encountered: ", sError, "\nPress Enter to Exit..."));

    // Dispose memory
    delete workbook;

    Console::ReadLine();

    return 0;
}