Memory management technology in C++

In C programming, memory management technology is a very important topic. Proper use of memory management technology can help us write efficient and robust programs and avoid problems such as memory leaks and wild pointers. This article will introduce the main memory management technologies in C, including:

1. new/delete operator

The new and delete operators in C are used to dynamically allocate and release memory. main means. The new operator allocates a memory of a specified size on the heap and returns a pointer to the memory. The delete operator can release the memory pointed to by the specified pointer. For example:

int* p = new int; // 在堆上分配一块大小为sizeof(int)的内存
*p = 10; // 往该内存写入一个int值
delete p; // 释放该内存

It should be noted that for dynamic memory allocation of array types, the new and delete operators with square brackets should be used.

2. RAII (resource acquisition is initialization)

RAII is a memory management method based on the object life cycle. Its core idea is that the allocation of any dynamic resources should be done in the object constructor, and the release should be done in the object destructor. In this way, when the program control flow leaves the object scope, the resources will be automatically released. This approach can effectively avoid memory leaks and other similar problems. For example:

class IntArray {
public:
    IntArray(int size) {
        data = new int[size]; // 在构造函数中分配内存
        len = size;
    }
    ~IntArray() {
        delete[] data; // 在析构函数中释放内存
    }
private:
    int* data;
    int len;
};

// 使用IntArray类来管理动态数组内存
IntArray arr(10);
arr[0] = 1;
arr[1] = 2;
// 离开arr作用域时，arr对象会自动释放内存

3. Smart pointer

A smart pointer is a pointer object that encapsulates dynamically allocated memory and automatically releases the memory at the end of the object's life cycle. Unlike traditional raw pointers, smart pointers can detect whether memory is still in use through reference counting or other methods, thereby avoiding problems such as wild pointers. std::unique_ptr and std::shared_ptr introduced in C 11 are two common smart pointer implementations. For example:

//使用unique_ptr管理动态数组内存
std::unique_ptr<int[]> p(new int[10]);  // 在构造时动态分配10个int的内存
p[0] = 1;
p[1] = 2;
// 离开p作用域时，p会自动释放内存

//使用shared_ptr管理动态数组内存
std::shared_ptr<int> sp = std::make_shared<int>(42);
// 可以使用lambda表达式来自定义删除器
std::shared_ptr<int> sp2(new int[10], [](int* p) {
    delete[] p;
});

4. STL container

STL provides a series of memory-safe containers, such as std::vector, std::string, std::list, etc. . They can automatically manage dynamic memory allocation and release, avoiding the trouble and potential errors of manual memory manipulation. For example:

// 使用std::vector管理动态数组内存
std::vector<int> vec(10); // 在构造时动态分配10个int的内存
vec[0] = 1;
vec[1] = 2;
// 离开vec作用域时，vec会自动释放内存

In short, in C, reasonable use of memory management technology can help us write efficient and robust programs. The techniques introduced above are just the tip of the iceberg of memory management in C. There are many other techniques that need to be continuously learned and mastered in actual programming.

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