C++学习日志18--nullptr空指针、内存的申请和释放

---

一、nullptr空指针

int main()
{
    
    

    auto x  {
    
     10 };
    int* p = nullptr;
    int* q;
    q = & x;

    int* p, a = 3;
    p = &a;


    return 0;

   
}

二、内存的申请和释放

int main()
{
    
    

    int* p = nullptr;
    int* q  {
    
     nullptr };

    p = new int(42);
    q = new int[4];

    std::cout << "before:*p=" << *p << std::endl;
    *p = 24;
    std::cout << "after * p=" << *p << std::endl;

    for (int i = 0; i < 4; i++)
    {
    
    
        *(q + i) = 10 + i;
        std::cout << *(q + i) << std::endl;
    }

    delete p;
    delete[]q;


    std::cin.get();
    return 0;

   
}

C++中使用new 和 delete 申请与释放内存，申请的内存若不及时释放，容易产生内存泄漏。