How to prevent the program from exiting until a certain character is pressed?

Question

linux

The question is extremely banal, and yet the solution does not want to come to my head in any way .. It also does not work out to formulate the question concisely and competently for a Google query.
The point is this. It is necessary to make sure that the console program does not terminate upon completion of execution, but waits for a certain button to be pressed. The behavior should be the same regardless of the layout for both Windows and Linux.
It could be done.
gets();
But I read somewhere that it is highly undesirable to do so.