what happened if an exception is not captured?

Question

I am not asking an unexpected exception, but an exception that is not captured.

Crashed? Or terminated?

Answer 1

According to §15.3/9:

If no matching handler is found in a program, the function terminate() is called; whether or not the stack is unwound before this call to terminate() is implementation-defined (15.5.1). _{Emphasis mine}

What happens after that is up to your OS. In practice: a crash. (Or if you're in a debugger, "Hey, you didn't catch this.")

Answer 2

Typically terminate will call abort() which quits the process, possibly dumping a core, or if a debugger is attached, stops in the debugger so you can see what happened. If you don't catch the exception somewhere, the program cannot continue.