std::set_terminate

 

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Defined in header <exception>
std::terminate_handler set_terminate( std::terminate_handler f ) throw();		(until C++11)
std::terminate_handler set_terminate( std::terminate_handler f ) noexcept;		(since C++11)

Makes f the new global terminate handler function and returns the previously installed std::terminate_handler. f shall terminate execution of the program without returning to its caller, otherwise the behavior is undefined.

This function is thread-safe. Every call to std::set_terminate synchronizes-with (see std::memory_order) subsequent calls to std::set_terminate and std::get_terminate.

(since C++11)

Parameters

f

-

pointer to function of type std::terminate_handler, or null pointer

Return value

The previously-installed terminate handler, or a null pointer value if none was installed.

Example

Run this code

#include <cstdlib>
#include <exception>
#include <iostream>
 
int main()
{
    std::set_terminate([]()
    {
        std::cout << "Unhandled exception\n" << std::flush;
        std::abort();
    });
    throw 1;
}

Possible output:

Unhandled exception
bash: line 7:  7743 Aborted                 (core dumped) ./a.out

The terminate handler will also work for launched threads, so it can be used as an alternative to wrapping the thread function with a try/catch block. In the following example, since the exception is unhandled, std::terminate will be called.

Run this code

#include <iostream>
#include <thread>
 
void run()
{
    throw std::runtime_error("Thread failure");
}
 
int main()
{
    try
    {
        std::thread t{run};
        t.join();
        return EXIT_SUCCESS;
    }
    catch (const std::exception& exc)
    {
        std::cerr << "Exception: " << exc.what() << '\n';
    }
    catch (...)
    {
        std::cerr << "Unknown exception caught\n";
    }
    return EXIT_FAILURE;
}

Possible output:

terminate called after throwing an instance of 'std::runtime_error'
  what():  Thread failure
Aborted (core dumped)

With the introduction of the terminate handler, the exception thrown from the non-main thread can be analyzed, and exit can be gracefully performed.

Run this code

#include <iostream>
#include <thread>
 
class foo
{
public:
    foo() { std::cerr << "foo::foo()\n"; }
    ~foo() { std::cerr << "foo::~foo()\n"; }
};
 
// Static object, expecting destructor on exit
foo f;
 
void run()
{
    throw std::runtime_error("Thread failure");
}
 
int main()
{
    std::set_terminate([]()
    {
        try
        {
            std::exception_ptr eptr{std::current_exception()};
            if (eptr)
            {
                std::rethrow_exception(eptr);
            }
            else
            {
                std::cerr << "Exiting without exception\n";
            }
        }
        catch (const std::exception& exc)
        {
            std::cerr << "Exception: " << exc.what() << '\n';
        }
        catch (...)
        {
            std::cerr << "Unknown exception caught\n";
        }
        std::exit(EXIT_FAILURE);
    });
 
    std::thread t{run};
    t.join();
}

Output:

foo::foo()
Exception: Thread failure
foo::~foo()

See also

terminate	function called when exception handling fails (function)
get_terminate (C++11)	obtains the current terminate_handler (function)
terminate_handler	the type of the function called by std::terminate (typedef)