How to debug a program that is terminating in an unhandled exception???

Question

Hi all,

I am programming in C++ on Linux platform.

My program terminates with this (unhandled???) exception:

"terminate called after throwing an instance of 'long'" Aborted

The code that is throwing the exception is inside try-catch block, then why should this happen?? The exception is thrown while returning from a function.

I am used to C programming and have very little experience in C++ (which is the main problem). I don't know how to debug this issue. I don't expect a solution but a direction/pointer for debugging this problem.

Thanks in advance.

Answer 1

you are probably catching the wrong exception type

use

catch(long)

or

catch(...)

Answer 2

It there anywhere on the call-stack with a exception specification or here? If there is then you might have this problem - you probably want to remove all of them.

If you are using gcc, then you can add this code first thing in main():

#ifdef __GNUC__
    std::set_terminate(__gnu_cxx::__verbose_terminate_handler);
#endif // ifdef __GNUC__

(More details at http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt02ch06s02.html)
Which will give you a better traceback from such exceptions.

Answer 3

Normally, I would recommend to set a breakpoint in the constructor of the thrown type -- but in this case ... I must admit to never have experienced that somebody has thrown a long like

throw 42;

That seems to me strange. Some debuggers might be able to catch an exception when it is thrown.

Is the called function yours?

Answer 4

You can run your application under gdb (having built it with debug info using -g) and get it to break when an exception is thrown using the command:

(gdb) catch throw

This will take you to the origin of the exception. Some more info is available in this question:

• Run an application in GDB until an exception occurs

Note that it is somewhat unusual to throw an ordinal type (such as a long). It may be in some temporary code, so grepping around might find it quickly enough.

Answer 5

Use set_terminate to break GDB

Example for set_terminate() is here

When it trigged - use bt command in GDB to see backtrace