what destructor used for in c++

A destructor in C++ is a special member function that is used to clean up the resources allocated by an object when it is destroyed. It is the opposite of a constructor, which is used to initialize an object when it is created. The destructor is defined with the same name as the class, preceded by a tilde (~).

Here are the steps involved in the execution of a destructor:

1. When an object goes out of scope or is explicitly deleted using the delete keyword, the destructor is automatically called by the C++ runtime.
2. The destructor performs cleanup operations, such as releasing dynamically allocated memory, closing file handles, or freeing other resources that were acquired during the object's lifetime.
3. The destructor is executed in the reverse order of object construction. This means that if an object is composed of other objects, the destructors of the member objects are called first, followed by the destructor of the containing object.
4. After the destructor finishes its execution, the memory occupied by the object is deallocated and becomes available for reuse.

It is important to note that if a class does not define its own destructor, the compiler will automatically generate a default destructor. However, if the class acquires resources that need to be cleaned up, it is good practice to define a custom destructor to ensure proper resource management.

Example:

class MyClass {
public:
  // Constructor
  MyClass() {
    // Initialization code
  }

  // Destructor
  ~MyClass() {
    // Cleanup code
  }
};

int main() {
  // Create an object of MyClass
  MyClass obj;
  // Do something with the object

  // obj goes out of scope and the destructor is automatically called
  return 0;
}

In the example above, the MyClass constructor is called when an object obj of type MyClass is created. The destructor is automatically called when obj goes out of scope at the end of the main function. The destructor can be used to release any resources acquired by the object during its lifetime.

Please note that the actual cleanup code inside the destructor will depend on the specific requirements of the class and the resources it manages.