try-catch usage

[vmnvmcxbv]

Why does this:

try
{
throw 1;
}
catch(...)
{
handle_exceptio n();
}

works as expected (exception is caught in the catch block)

and this:

try
{
throw;
}
catch(...)
{
handle_exceptio n();
}

crashes application? Isn't catch(...) supposed to catch _everything_?

FWIW - I use VC++ 2008

[Obnoxious User]

Re: try-catch usage

On Tue, 26 Aug 2008 12:01:20 +0000, vmnvmcxbv wrote:

Why does this:
>
try
{
throw 1;
}
catch(...)
{
handle_exceptio n();
}
>
works as expected (exception is caught in the catch block)
>
and this:
>
try
{
throw;

I doubt this statement is even allowed here. It is used within
catch handlers to rethrow the exception so it can be catched
again somewhere.

--
OU

[Ali Karaali]

Re: try-catch usage

On 26 Aðustos, 15:01, "vmnvmcxbv" <ruyeir...@fhsd khf.netwrote:

Why does this:
>
try
{
    throw 1;}
>
catch(...)
{
    handle_exceptio n();
>
}
>
works as expected (exception is caught in the catch block)
>
and this:
>
try
{
    throw;}
>
catch(...)
{
    handle_exceptio n();
>
}

The catch can catch everything but you don't throw anything.
So calling std::terminate( ) function

[red floyd]

Re: try-catch usage

On Aug 26, 5:01 am, "vmnvmcxbv" <ruyeir...@fhsd khf.netwrote:

Why does this:
>
try
{
    throw 1;}
>
catch(...)
{
    handle_exceptio n();
>
}
>
works as expected (exception is caught in the catch block)
>
and this:
>
try
{
    throw;}
>
catch(...)
{
    handle_exceptio n();
>
}
>
crashes application? Isn't catch(...) supposed to catch _everything_?
>

Per 15.1/8, "If no exception is presently being handled, executing a /
throw-expression/ with no operand calls terminate()."

In other words, a "throw;" must occur inside a catch block, or you
will be terminated.

[Christian Hackl]

Re: try-catch usage

red floyd wrote:

Per 15.1/8, "If no exception is presently being handled, executing a /
throw-expression/ with no operand calls terminate()."
>
In other words, a "throw;" must occur inside a catch block, or you
will be terminated.

I think that's too narrow. An exception can be handled even if you are
not currently inside of a catch block, can't it?

#include <exception>
#include <stdexcept>
#include <iostream>

void handleException ()
{
try
{
throw;
}
catch (std::exception const &exc)
{
std::cout << exc.what() << "\n";
}
catch (...)
{
std::cout << "unknown exception\n";
}
}

int main()
{
try
{
throw std::runtime_er ror("test");
}
catch (...)
{
handleException ();
}
}

Isn't this a perfectly standard-conforming program? It does not call
terminate() when compiled and run with VC or GCC.


--
Christian Hackl

[Pete Becker]

Re: try-catch usage

On 2008-08-26 12:44:48 -0400, Christian Hackl <hacki@sbox.tug raz.atsaid:

red floyd wrote:
>

>Per 15.1/8, "If no exception is presently being handled, executing a /
>throw-expression/ with no operand calls terminate()."
>>
>In other words, a "throw;" must occur inside a catch block, or you
>will be terminated.

>
I think that's too narrow. An exception can be handled even if you are
not currently inside of a catch block, can't it?

It depends on just what you mean by "inside" a catch block. Most people
would say that the throw; below is inside a catch block. If you call
handleException directly from main, i.e. not inside any catch block,
the program will, indeed, be terminated.

>
#include <exception>
#include <stdexcept>
#include <iostream>
>
void handleException ()
{
try
{
throw;
}
catch (std::exception const &exc)
{
std::cout << exc.what() << "\n";
}
catch (...)
{
std::cout << "unknown exception\n";
}
}
>
int main()
{
try
{
throw std::runtime_er ror("test");
}
catch (...)
{
handleException ();
}
}
>
Isn't this a perfectly standard-conforming program? It does not call
terminate() when compiled and run with VC or GCC.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)