make Derive final, C++ (vc++)

Language: Layout:

#include <iostream>
#include <cstdlib>
#include <iostream>
#include <chrono>
#include <vector>
class A{
    public: int f1(){return randomNumber*3;};
    public: virtual int f2(){return randomNumber*3;};
    public: virtual int f3(){return randomNumber*3;};
    public: int f4(){return f3();};
    public: int randomNumber=((double) rand() / (RAND_MAX))*10;
   
};
class B  final : public A {
    public: virtual int f2() {return randomNumber*4;};
    public: virtual int f3()final {return randomNumber*4;};
};

int main(){
    std::vector<B*> bs;
    const int numTest=10000;
    for(int n=0;n<numTest;n++){
        bs.push_back(new B());
    };
    int accu=0;

for(int n=0;n<numTest;n++){
        accu+=bs[n]->f1();  //warm
    };
    auto t1= std::chrono::system_clock::now();
    for(int n=0;n<numTest;n++){
        accu+=bs[n]->f1();  //test 1 : base case, non virtual
    };
    auto t2= std::chrono::system_clock::now();
        for(int n=0;n<numTest;n++){
        accu+=bs[n]->f2();  //test 2: virtual 
    };
    auto t3= std::chrono::system_clock::now();
    for(int n=0;n<numTest;n++){
        accu+=bs[n]->f3();  //test 3: virtual & final
    };
    auto t4= std::chrono::system_clock::now();
    for(int n=0;n<numTest;n++){
        accu+=bs[n]->f4();  //test 4: virtual & final & encapsulator
    };
    auto t5= std::chrono::system_clock::now();
    auto t21=t2-t1;
    auto t32=t3-t2;
    auto t43=t4-t3;
    auto t54=t5-t4;
     std::cout<<"test1 base                      ="<<t21.count()<<std::endl;    
     std::cout<<"test2 virtual                   ="<<t32.count()<<std::endl;
     std::cout<<"test3 virtual & final           ="<<t43.count()<<std::endl;
     std::cout<<"test4 virtual & final & indirect="<<t54.count()<<std::endl;
     std::cout<<"forbid optimize"<<accu;
}

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Compilation time: 1,81 sec, absolute running time: 0,32 sec, absolute service time: 2,14 sec