(C++) Answer of exercise #9: No for-loops #4

 

This is the answer of Exercise #9: No for-loops.

 

• Download the Qt Creator project 'CppExerciseNoForLoopsAnswer4' (zip)

 

 

 

 

 

Question #4: Widget::DoIt on Widget

 

Replace the for-loop. You will need std::for_each and std::mem_fun_ref.

 

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#include <vector> struct Widget {   void DoIt() const { /* do it */ } }; void DoIt(const std::vector<Widget>& v) {   const int sz = static_cast<int>(v.size());   for (int i=0; i!=sz; ++i)   {     v[i].DoIt();   } }

 

 

 

 

 

Answer using C++98 its STL

 

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#include <algorithm> #include <functional> #include <numeric> #include <vector> struct Widget {   void DoIt() const { /* do it */ } }; void DoIt(const std::vector<Widget>& v) {   std::for_each(v.begin(),v.end(),std::mem_fun_ref(&Widget::DoIt)); }

 

 

 

 

 

Answer using C++98 and Boost

 

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#include <algorithm> #include <vector> #include <boost/mem_fn.hpp> struct Widget {   void DoIt() const { /* do it */ } }; void DoIt(const std::vector<Widget>& v) {   std::for_each(v.begin(),v.end(),boost::mem_fn(&Widget::DoIt)); }

 

 

 

 

 

Answer using C++11 its STL

 

Instead of using a functor, use a lambda expressions.

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#include <algorithm> #include <vector> void DoIt(const std::vector<Widget>& v) {   std::for_each(v.begin(),v.end(),[](const Widget& w) { w.DoIt(); } ); }