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| #include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <ctime>
#include <math.h>
class Mytimer
{
public:
Mytimer() {Restart();};
void Restart() {m_start_time = std::clock();}
double GetTime() {return double(std::clock() - m_start_time) / CLOCKS_PER_SEC;}
private:
std::clock_t m_start_time;
};
struct MyGenerate
{
explicit MyGenerate()
:count_(0)
{}
int operator () () {count_++ ; return static_cast<int> ( sqrt(count_*count_+36) );}
private:
int count_;
};
const long int my_vect_size = 300000;
const int nb_compute =50;
std::vector<int> my_vect;
std::vector<int>::iterator It1;
std::vector<int>::iterator Itend;
std::vector<double> genTime1;
std::vector<double> genTime2;
std::vector<double> genTime3;
std::vector<double> genTime4;
struct ecart_type
{
ecart_type(double & moyenne): m_moyenne (moyenne),m_somme(0.),m_NbElements(0){};
void operator()(const double & val )
{
double x = val-m_moyenne;
m_somme+=x*x;
++m_NbElements;
}
double GetEcartType(){return std::sqrt(m_somme/m_NbElements);}
double m_moyenne;
double m_somme;
int m_NbElements;
};
void AFFICHER_resultat(std::vector<double>& vect)
{
std::cout << "min : "<<*std::min_element(vect.begin(),vect.end())<<std::endl;
std::cout << "max : "<<*std::max_element(vect.begin(),vect.end())<<std::endl;
double moyenne = std::accumulate(vect.begin(),vect.end(),0.)/vect.size();
std::cout << "moyenne : "<<moyenne<<std::endl;
ecart_type ect = std::for_each(vect.begin(),vect.end(),ecart_type(moyenne));
std::cout << "ecart type : "<<ect.GetEcartType()<<std::endl;
}
void gen1(int n)
{
Mytimer time__;
MyGenerate gen;
It1 = my_vect.begin();
for (It1 = my_vect.begin();It1!=my_vect.end(); ++It1)
{
*It1 = gen();
}
genTime1.push_back( time__.GetTime());
}
void gen2(int n)
{
Mytimer time__;
MyGenerate gen;
It1 = my_vect.begin();
Itend = my_vect.end();
for (It1 = my_vect.begin();It1!=Itend; ++It1)
{
*It1 = gen();
}
genTime2 .push_back( time__.GetTime());
}
void gen3(int n)
{
Mytimer time__;
int i=0;
MyGenerate gen;
for(int i=0; i<my_vect.size();++i)
{
my_vect[i] = gen();
}
genTime3 .push_back( time__.GetTime());
}
void gen4(long int n)
{
Mytimer time__;
std::generate( my_vect.begin(), my_vect.end(), MyGenerate() );
genTime4 .push_back( time__.GetTime());
}
int main()
{
my_vect.resize(my_vect_size);
int i = 0;
for (i = 0 ; i<nb_compute ; i++)
{
std::cerr<<100.*(static_cast<float>(i)/(nb_compute-1))<<"% \r";
gen1(my_vect_size);
gen2(my_vect_size);
gen3(my_vect_size);
gen4(my_vect_size);
}
std::cout <<std::endl;
std::cout << "gen time 1" << std::endl;
AFFICHER_resultat(genTime1);
std::cout <<std::endl<< "gen time 2" << std::endl;
AFFICHER_resultat(genTime2);
std::cout << std::endl<<"gen time 3" << std::endl;
AFFICHER_resultat(genTime3);
std::cout << std::endl<<"gen time 4 " << std::endl;
AFFICHER_resultat(genTime4);
return 0;
} |
