Rethrow propagate exception

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Sometimes you want to do something with the exception you catch (like write to log or print a warning) and let it bubble up to the upper scope to be handled. To do so, you can rethrow any exception you catch:

try {
    ... // some code here
} catch (const SomeException& e) {
    std::cout << "caught an exception";

Using throw; without arguments will re-throw the currently caught exception.

To rethrow a managed std::exception_ptr, the C++ Standard Library has the rethrow_exception function that can be used by including the <exception> header in your program.

#include <iostream>
#include <string>
#include <exception>
#include <stdexcept>
void handle_eptr(std::exception_ptr eptr) // passing by value is ok
    try {
        if (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
} // destructor for std::out_of_range called here, when the eptr is destructed
Caught exception "basic_string::at: __n (which is 1) >= this->size() (which is 0)"

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