How are smart destruction and exception safety implemented in C++ smart pointers?

Answer: Smart destruction and exception-safe implementation: Smart pointers use overridden destructors to support automatic calling of the destructor after the object pointed to by the pointer goes out of scope. They use exception guarantee classes to ensure that the destructor is always called when an exception occurs to ensure that the object is released correctly. Smart destruction: Override the destructor (~) operator to automatically release objects when they go out of scope. Exception safety: Use exception protection classes to ensure that the destructor is always called when an exception occurs. Practical case: Managing dynamically allocated objects to prevent memory leaks and simplifying code

Smart destruction and exception safety implementation in C++ smart pointers

Introduction

Smart pointers are a C++ language feature that combines pointers with mechanisms to manage their lifetime and release. They provide the following advantages:

• Automatic memory management
• Exception safety
• Smart destruction

This article will focus on smart pointers Intelligent destruction and exception safety implementation mechanism.

Smart Destruction

Smart pointers support automatically calling the destructor after the object pointed to by the pointer goes out of scope. This is accomplished by overriding the ~ (destructor) operator. In the following example, UniquePtr automatically releases the object it manages after going out of scope:

#include <memory>

int main() {
  std::unique_ptr<int> ptr(new int(5));
}

Smart pointers use a destructor pointer to track the object they manage and call it when it goes out of scope. The pointer to release the object.

Exception safety

Smart pointers use the exception safety mechanism to ensure that the pointed object is released when an exception occurs. This is accomplished using a set of classes called Exception Guarantees. These classes are responsible for ensuring that the destructor is always called when an exception occurs, even if an exception occurs.

For example, std::shared_ptr uses exception guarantees to handle pointers to shared ownership objects. It ensures that when an exception is thrown and stack unwinding is cancelled, the ownership count is properly decremented and the object is properly released:

#include <memory>

int main() {
  try {
    std::shared_ptr<int> ptr = std::make_shared<int>(5);
    throw std::runtime_error("异常已抛出");
  } catch (...) {
    // 指针 ptr 已在异常抛出时释放
  }
}

Practical Case

Smart pointers are useful in many scenarios Useful, including:

• Manage dynamically allocated objects
• Prevent memory leaks
• Simplify code

The following is an example to demonstrate How to use smart pointers to manage dynamically allocated objects:

#include <memory>

class MyClass {
public:
  MyClass() { std::cout << "构造 MyClass" << std::endl; }
  ~MyClass() { std::cout << "析构 MyClass" << std::endl; }
};

int main() {
  std::unique_ptr<MyClass> ptr = std::make_unique<MyClass>();
}

Running this code produces the following output:

构造 MyClass
析构 MyClass

This output indicates that the object was properly initialized and released.

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