Quick vector copy

Hi, what is the quickest (most processor efficient) way of copying from one vector to another?

thanks.

Do you want to copy the entire vector, or just a part of it?

The entire vector is all I need.

I'm currently copying it all using a loop and pushing each item from the source vector to the target vector one at a time - but I'm trying to optimize my code.

thanks,

Code:

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#include<vector>
#include<iostream>
using namespace std;

int main()
{
        vector<int> v1;
        v1.push_back(10);
        v1.push_back(5);
        v1.push_back(9);
        // You can initialize a vector from another
        vector<int>v2(v1);
        // You can assign a vector to another
        vector<int> v3;
        v3 = v2;
       
        cout << v3[0] << ", " << v3[1] << ", " << v3[2] << endl;
        // outputs: 10, 5, 9
}

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If you won't need your source vector after the copy, the quickest way is to use swap because it doesn't actually copy anything.

Code:

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v1.swap(v2);

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Otherwise, initialization or assignment as Darryl showed is the best way (assuming both vectors hold the same type).

that's great - thanks