Re: Can I avoid the use of arrays in this situation or do I have to use them?

turninng debug switch off I found the following two sequences almost
equivalent in time:

1.vector buf ; swap ;
2. array buf ; fill ; result.reserve ; copy ;

#include <iostream>
#include <conio.h>
#include <vector>
#include <string>
#include <Ctime>
using namespace std;

enum {sz=1000,loop=100*1000};

void vec1(){
        vector <int> v(sz),dest;
        v.swap(dest);

}

void vec0(){
        vector <int> v,dest;
        v.reserve(sz);
        fill(v.begin(),v.begin()+v.capacity(),0);
        v.swap(dest);

}

void vec2(){
        vector <int> v(sz),dest;
        swap(dest,v);

}

void arr(){
        int arr[sz];
        vector <int> dest;
        fill(arr,&(arr[sz]),0);
        dest.reserve(sz);
        copy(arr,&arr[sz],dest.begin());

}

template <typename pred>
void test(pred f,string txt){
        cout<<("testing:"+txt)<<endl;
        const clock_t c=clock();
        for(int i=0;i<loop;i++)
                f();
        cout<<clock()-c<<" ms"<<endl;

}

int main()
{
        vector<A> v1(sz);
        cout << "\nvector * i=" << A::get() << endl ;
        A::get()=0;
        vector<A> v2;
        v2.reserve(sz);
        cout << "reserve * i=" << A::get() << endl ;
        test(vec0,"reserve");
        test(vec1,"vector");
        test(vec2,"std::swap");
        test(arr,"array");
        getch();
        return 0;

}

output:

testing:reserve
1172 ms
testing:vector
1141 ms
testing:std::swap
1125 ms
testing:array
1141 ms

regards,
FM.