Grusel++ of the month

/******************************************************************************/
/*                                                                            */
/*                                                          FILE: october.cpp */
/*                                                                            */
/*  Demostrates the effect of the mutable qualifier                           */
/*  ===============================================                           */
/*                                                                            */
/*  Compiled and tested with Visual Studio .NET 2003                          */
/*                                                                            */
/*  V1.00   30-OCT-2003   P. Tellenbach   http://www.heimetli.ch/             */
/*                                                                            */
/******************************************************************************/

#include <iostream>
#include <string>

using namespace std ;

class MutableConst
{
 protected:
   mutable string str ;

 public:
   MutableConst( const char *s ) : str(s)
   {
   }

   void twist( const char *s ) const
   {
       string::iterator it = str.begin() ;

       while( ++it != str.end() )
          it = ++str.insert( it, *s++ ) ;
   }

   void print() const
   {
       cout << str << endl ;
   }
} ;

int main()
{
   const MutableConst mc( "Hlowrd!" ) ;

   mc.twist( "el ol " ) ;
   mc.print() ;

   return 0 ;
}

Update 31. October 2023

This program compiles and runs without any changes.