set_new_handler例子

#include <iostream>

/// buffer to be allocated after custom new handler has been installed

char* g_pSafetyBuffer = NULL;

/// exceptional one time release of a global reserve

void my_new_handler()

{

    if (g_pSafetyBuffer) {

        delete [] g_pSafetyBuffer;

        g_pSafetyBuffer = NULL;

        std::cout << "[Free some pre-allocated memory]";

        return;

    }

    std::cout << "[No memory to free, throw bad_alloc]";

    throw std::bad_alloc();

}

/// illustrates how a custom new handler may work

int main()

{

    enum { MEM_CHUNK_SIZE = 1000*1000 }; // adjust according to your system

    std::set_new_handler(my_new_handler);

    g_pSafetyBuffer = new char[801*MEM_CHUNK_SIZE];

    try {

        while (true) {

            std::cout << "Trying another new... ";

            new char[200*MEM_CHUNK_SIZE];

            std::cout << " ...succeeded.\n";

        }

    } catch (const std::bad_alloc& e) {

        std::cout << " ...failed.\n";

    }

    return 0;

}