std:: set_new_handler

Makes new_p the new global new-handler function and returns the previously installed new-handler.

The new-handler function is the function called by allocation functions whenever a memory allocation attempt fails. Its intended purpose is one of three things:

The default implementation throws std::bad_alloc . The user can install their own new-handler , which may offer behavior different than the default one.

If new-handler returns, the allocation function repeats the previously-failed allocation attempt and calls the new-handler again if the allocation fails again. To end the loop, new-handler may call std :: set_new_handler ( nullptr ) : if, after a failed allocation attempt, allocation function finds that std::get_new_handler returns a null pointer value, it will throw std::bad_alloc .

At program startup, new-handler is a null pointer.

Parameters

Return value

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

Example

#include <iostream>
#include <new>
 
void handler()
{
    std::cout << "Memory allocation failed, terminating\n";
    std::set_new_handler(nullptr);
}
 
int main()
{
    std::set_new_handler(handler);
    try
    {
        while (true)
        {
            new int[1000'000'000ul]();
        }
    }
    catch (const std::bad_alloc& e)
    {
        std::cout << e.what() << '\n';
    }
}

Memory allocation failed, terminating
std::bad_alloc

See also