std::current_exception (3) Linux Manual Page

std::current_exception – std::current_exception

Synopsis

Defined in header <exception>
std::exception_ptr current_exception() noexcept; (since C++11)
If called during exception handling (typically, in a catch clause), captures the current exception object and creates an std::exception_ptr that holds either a copy or a reference to that exception object (depending on the implementation). The referenced object remains valid at least as long as there is an exception_ptr object that refers to it.
If the implementation of this function requires a call to new and the call fails, the returned pointer will hold a reference to an instance of std::bad_alloc.
If the implementation of this function requires copying the captured exception object and its copy constructor throws an exception, the returned pointer will hold a reference to the exception thrown. If the copy constructor of the thrown exception object also throws, the returned pointer may hold a reference to an instance of std::bad_exception to break the endless loop.
If the function is called when no exception is being handled, an empty std::exception_ptr is returned.

Parameters

(none)

Return value

An instance of std::exception_ptr holding a reference to the exception object, or a copy of the exception object, or to an instance of std::bad_alloc or to an instance of std::bad_exception.

Example

// Run this code

#include <iostream>

#include <string>

#include <exception>

#include <stdexcept>
void handle_eptr(std::exception_ptr eptr) // passing by value is ok

{
    try {
        if (eptr) {
            std::rethrow_exception(eptr);
        }
    } catch (const std::exception &e) {
        std::cout << "Caught exception \"" << e.what() << "\"\n";
    }
}
int main()

{
    std::exception_ptr eptr;
    try {
        std::string().at(1); // this generates an std::out_of_range
    } catch (...) {
        eptr = std::current_exception(); // capture
    }
    handle_eptr(eptr);

} // destructor for std::out_of_range called here, when the eptr is destructed

Output:

  Caught exception "basic_string::at"

See also

exception_ptr shared pointer type for handling exception objects
                   (typedef)
(C++11)
rethrow_exception throws the exception from an std::exception_ptr
                   (function)
(C++11)
make_exception_ptr creates an std::exception_ptr from an exception object
                   (function template)
(C++11)