very basic C++ program closes after user input for no particular reason?

Question

I just started learning C++ and I wrote this sample program from the text and when I compile and run it, it just closes after the user inputs any number and presses enter.

Answer 1

It closes because the execution reaches return 0; and there is nothing left to do.

If you want the program to wait before closing you could add an something like this:

cout << "Press enter to exit...";
cin  >> someVarThatWontBeUsed;

You could also run the program from the command line instead of running the .exe. It will reach end of execution anyway but the prompt will stay open.