C++ Exceptions Rethrow (propagate) exception
Example
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";
throw;
}
Using throw; without arguments will re-throw the currently caught exception.
C++11
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) {
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
