8 Expressions [expr]

8.17 Throwing an exception [expr.throw]

throw-expression:
	throw  assignment-expression $_{o p t}$

A throw-expression is of type void.

Evaluating a throw-expression with an operand throws an exception ([except.throw]); the type of the exception object is determined by removing any top-level cv-qualifiers from the static type of the operand and adjusting the type from “array of T” or function type T to “pointer to T”.

A throw-expression with no operand rethrows the currently handled exception ([except.handle]).

The exception is reactivated with the existing exception object; no new exception object is created.

The exception is no longer considered to be caught.

[ Example

Code that must be executed because of an exception, but cannot completely handle the exception itself, can be written like this:

try {
    // ...
} catch (...) {     // catch all exceptions
  // respond (partially) to exception
  throw;            // pass the exception to some other handler
}

— end example

]

If no exception is presently being handled, evaluating a throw-expression with no operand calls std::terminate() ([except.terminate]).