What is ${} ing called?

It’s been a long time since my last practice using C++, so a bit rusty here, but AFAI-can-tell that’s not how you print a text with variable between them.

int x=23;
cout << "They have prepared" << int << "cakes with honey and butter.";

https://www.w3schools.com/cpp/cpp_variables.asp


Otherwise, the good 'ol way

cout << "They have prepared";
cout << int;
cout << "cakes with honey and butter.";