std::set_terminate
(C++17)<exception>
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 .
Contents
[edit] Parameters
[edit] Return value
The previously-installed terminate handler, or a null pointer value if none was installed.
[edit] Example
#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.
#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 & ex) { std::cerr << "Exception: " << ex.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.
#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 & ex) { std::cerr << "Exception: " << ex.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()