(C++) StdMemcpyExample2

 

Technical facts

 

Operating system(s) or programming environment(s)

• Lubuntu 15.04 (vivid)

IDE(s):

• Qt Creator 3.1.1

Project type:

• Console application

C++ standard:

• C++98

Compiler(s):

• G++ 4.9.2

Libraries used:

• STL: GNU ISO C++ Library, version 4.9.2

 

 

 

 

 

Qt project file: ./CppStdMemcpyExample2/CppStdMemcpyExample2.pro

 

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include(../../ConsoleApplication.pri) SOURCES += main.cpp

 

 

 

 

 

./CppStdMemcpyExample2/main.cpp

 

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#include <cassert> #include <iostream> #include <cstring> #include <chrono> #include <vector> template<class T> void CopyStl(const std::vector<T>& from, std::vector<T>& to) {   assert(from.size() == to.size());   std::copy(std::begin(from),std::end(from),std::begin(to)); } template<class T> void CopyMemcpy(const std::vector<T>& from, std::vector<T>& to) {   assert(from.size() == to.size());   assert(from.size() * sizeof(int) > 0);   std::memcpy(&to[0],&from[0],from.size() * sizeof(int)); } int main() {   using Clock = std::chrono::high_resolution_clock;   using Duration = std::chrono::system_clock::duration;   using TimePoint = std::chrono::high_resolution_clock::time_point;   using Msecs = std::chrono::milliseconds;   const int sz{100000000};   const int n{100};   const std::vector<int> from(sz);   std::vector<int> to(from.size());   const TimePoint t_stl_begin{Clock::now()};   for (int i=0; i!=n; ++i) { CopyStl(from,to); }   const Duration t_stl_time{Clock::now() - t_stl_begin};   const TimePoint t_memcpy_begin{Clock::now()};   for (int i=0; i!=n; ++i) { CopyMemcpy(from,to); }   const Duration t_memcpy_time{Clock::now() - t_memcpy_begin};   #ifndef NDEBUG   std::cout << "Don't do profing in debug mode!" << std::endl;   #else   std::cout     << std::chrono::duration_cast<Msecs>(t_stl_time).count() << " milliseconds" << '\n'     << std::chrono::duration_cast<Msecs>(t_memcpy_time).count() << " milliseconds" << '\n'     << std::endl;   #endif } /* Screen output: 9222 milliseconds 9140 milliseconds Press <RETURN> to close this window... */