catch( const std::runtime_error & e)
{
....
}
When compile, met an error:
error: expected unqualified-id before &.
It was so puzzling.
With experence in C++, fixed it after including head file <stdexcept>.
Then may I understand unqualified-id as incomplete class? If so, this error message just says "need a type or class before & even it is incomplete". The implication is that runtime_error is nod declared or not declared as a class.
What's the meaning of unqualified-id?
原文：https://www.cnblogs.com/clblacksmith/p/10395212.html