How to avoid the risk of dangling pointers?

Tips to avoid the risk of dangling pointers include: 1. Initialize pointers; 2. Use RAII (automatic release of resources mechanism); 3. Use pointer wrappers; 4. Avoid manual release of memory; 5. Use debugging tools. This ensures that the pointer always points to valid memory and prevents access to freed memory from causing the program to crash.

How to avoid the risk of dangling pointers

A dangling pointer refers to a pointer pointing to released memory, which may lead to undefined Behavior and program crashes. Here are some tips to avoid dangling pointers:

1. Always initialize pointers

Be sure to initialize a pointer tonullptr before using it Or point to valid memory:

int* ptr = nullptr;

2. Use RAII (resource acquisition is initialization)

RAII is a technology for writing code that ensures that resources are automatically released. Smart pointers (such as std::unique_ptr and std::shared_ptr) are one way to implement RAII:

std::unique_ptr<int> ptr(new int(42));

3. Use pointer wrappers

Pointer wrappers can make pointers safer and easier to use. They provide access to the underlying pointer while also providing the protection of smart pointers:

class IntWrapper {
public:
    IntWrapper(int* ptr) : ptr(ptr) {}

    int* get() const { return ptr; }

    int& operator*() const { return *ptr; }
private:
    int* ptr;
};

4. Avoid manual delete

Manual callsdelete may cause the pointer to hang. Instead, use smart pointers or pointer wrappers to manage memory release.

5. Use debugging tools

Many compilers and debuggers provide tools to detect dangling pointers. For example, Valgrind is a memory debugger that can identify accesses to freed memory.

Practical case

Consider the following code:

int* ptr = new int(42);
delete ptr;
*ptr = 43; // 访问已释放内存！

This will cause the pointer to hang because ptr is changing its value 43 were previously deleted. To solve this problem, you can use smart pointers:

std::unique_ptr<int> ptr(new int(42));
*ptr = 43; // 安全

With smart pointers, the memory will be automatically released when ptr goes out of scope, thus preventing the pointer from dangling.

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