The following code example is taken from the book
C++23 - The Complete Guide
by Nicolai M. Josuttis,
Leanpub, 2026
The code is licensed under a
Creative Commons Attribution 4.0 International License.
// raw code
#include <print>
#include <string>
#include <flat_map>
int main()
{
std::flat_map<std::string, double> fm;
// "insert or update" some elements in(to) the collection:
fm["Rome"] = 18.5; // insert
fm["Kiev"] = 32.8; // insert
fm["London"] = 24.1; // insert
fm["Berlin"] = 22.6; // insert
std::println("{}", fm);
fm["London"] = 28.9; // update
std::println("{}", fm);
}