Question

How to use back_inserter to append all existing vector elements to the same vector in C++

Answer 1

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>

using std::vector;
using std::cout;
using std::endl;

void print(const vector<int>& vec)
{
	for (auto element : vec) {
		cout << element << ' ';
	}
	cout << std::endl;
}

int main()
{
	vector<int> vec;

	std::back_inserter(vec) = 1;
	std::back_inserter(vec) = 2;
	std::back_inserter(vec) = 3;
	print(vec);

	vec.reserve(3 * vec.size());
	copy(vec.begin(), vec.end(), std::back_inserter(vec));
	print(vec);
}


/*
run:

1 2 3
1 2 3 1 2 3

*/

 

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