#include <cstring>
 #include <chrono>
 #include <iostream>
 #include <type_traits>

 namespace my{

   template <typename I, typename T, bool b>
   void fill_impl(I first, I last, const T& val, const std::integral_constant<bool, b>&){
     while(first != last){
       *first = val;
       ++first;
     }
   }

   template <typename T>
   void fill_impl(T* first, T* last, const T& val, const std::true_type&){
     std::memset(first, val, last-first);
   }

   template <class I, class T>
   inline void fill(I first, I last, const T& val){
     typedef std::integral_constant<bool,std::has_trivial_copy_assign<T> ::value && (sizeof(T) == 1)> boolType;
     fill_impl(first, last, val, boolType());
   }
 }

 const int arraySize = 100000000;
 char charArray1[arraySize]= {0,};
 char charArray2[arraySize]= {0,};

 int main(){

   std::cout << std::endl;

   auto begin= std::chrono::system_clock::now();
   my::fill(charArray1, charArray1 + arraySize,1);
   auto last=  std::chrono::system_clock::now() - begin;
   std::cout <<  "charArray1: " << std::chrono::duration<double>(last).count() << " seconds" << std::endl;

   begin= std::chrono::system_clock::now();
   my::fill(charArray2, charArray2 + arraySize, static_cast<char>(1));
   last=  std::chrono::system_clock::now() - begin;
   std::cout <<  "charArray2: " << std::chrono::duration<double>(last).count() << " seconds" << std::endl;

   std::cout << std::endl;

 }