C ++：抛出异常怪异行为？

Question

I just noticed something, and I think it's pretty weird. It's not very important, but it draws my curiosity.

Imagine you declare a class:

class myException : public std::exception
{
    /*do stuff*/
} myExep;

I just noticed that whenever you throw that exception, you need to do it differently depending on whether you use myException or myExep :

try
{
    if (/*whatever*/)
         throw myException();
}

or :

try
{
    if (/*whatever*/)
         throw myExep;
}

I do not understand why you need () in one case and not the other. I use clang++ as compiler, dunno if it has anything to do with it. I use -Wall -Werror -Wextra flags.

It's not really a big deal, I just want to understand what really happens.

Answer 1

class Foo {
  ...
} bar;

is just a shorter way of writing

class Foo {
  ...
};
Foo bar;

You can also use this syntax without giving the type a name:

struct {
    int x, y;
} p;
// p is an object with p.x and p.y fields

In your example, myException is a type while myExp is a (presumably global) object.