Feel the change: Meet the new C++23 insert_range()

If you need to insert a range of elements in a container, C++23 allows you to do so using a single function call — because looping is so 2020.

C++23 brought a new and useful addition to the language: insert_range(). This new member function provides a more efficient way to insert a range of elements into a vector. Until C++23, the only way to insert a range of elements into a vector was to use a loop. For example:

std::vector<int> vec1 = {1, 2, 3, 4, 5};
std::vector<int> vec2 = {6, 7, 8, 9, 10}; 

for (int i = 0; i < vec2.size(); i++)
{
  vec1.insert(vec1.begin() + 2 + i, vec2[i]);
}
// Print the vector
for (int i = 0; i < vec1.size(); i++)
{ 
  std::cout << vec1[i] << " ";
}

Our output will be: 1 2 6 7 8 9 10 3 4 5

However, especially when we use large vectors, loops could be very inefficient. When you loop through a large container, you are essentially accessing each element in the container one at a time. This can be a very slow process, especially if the container is very large.

The insert_range() function solves this problem by providing a single function that can be used to insert a range of elements into a vector with a single function call. So now, instead of using the loop in our previous code, we can simply write:

std::vector<int> vec1 = {1, 2, 3, 4, 5};
std::vector<int> vec2 = {6, 7, 8, 9, 10};

auto iter = vec1.insert_range(vec1.begin() + 2, vec2.begin(), vec2.end());

for (int i = 0; i < vec1.size(); i++)
{
  std::cout << vec1[i] << " ";
}

As you can see, we don’t need to use a loop, we simply add the new range to our vector.

The new insert_range() function is a really valuable addition to the C++ language, and we expect it will be widely used.

In my new book, Learning C++, published by Manning Publications and co-written with Michael Haephrati, you can learn all about C++ core language, including new C++23 features.