I am using Dev-C++ and lambda expression.I wrote the following lines: .................. typedef std::map<int, int> IIPrimemap; IIPrimemap primemapvec; ..................... void a(){ primemapvec[1]=3; bind(&IIPrimemap::value_type::second,(*bind(static_cast<IIPrimemap::iterator (IIPrimemap::*)()> (&IIPrimemap::end),var(primemapvec))))++; return; } .................... but after the program ran, the primemapvec[1] is still 3, not 4. I am puzzled about that. How can I change primemapvec to 4 ? Can anyone with kindness help me?