Question:
How to proceed to add an element in the position that I indicate in a std::vector ? It's not to delete what you already have, but to add in the middle. Here's an example:
Let's suppose that inside a std::vector it has the elements
{1,2,3,4,5,6,7,8,9};
And I want to add a number before the 4 and after the 3, but without deleting any element, thus:
{1,2,3,10,4,5,6,7,8,9}
How to proceed? Is this possible to be done? Or do I need to use some other container , like list ?
Answer:
You can use the insert() method, but you need to create an iterator:
#include <iostream>
#include <vector>
int main () {
std::vector<int> vec {1, 2, 3, 4, 5, 6, 7, 8, 9};
auto it = vec.begin();
vec.insert(it + 3, 10);
for (auto x: vec) std::cout << ' ' << x;
}
See it working on ideone . And on repl.it. I also put it on GitHub for future reference .
If you do it correctly, measure and the performance doesn't please, then you need to use another framework that has other compromises. A list may be an option. It can do middle insertion with O(1) complexity. But other operations are not as fast as the vector . Don't fix one thing and break another. See what's a priority. Maybe another structure is more suitable. There is no perfect structure where everything is great.