Quick vector copy

[Nolens]

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

thanks.

[Decrypt]

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

[Nolens]

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,

[Darryl]

#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
}

[Daved]

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.

v1.swap(v2);

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

[Nolens]

that's great - thanks