Destructor

A destructor is a special member function that runs when an object is destroyed. It has the same name as the class with a leading ~, no parameters, and no return type:

class Logger {
public:
  Logger() { std::cout#include <iostream> << "created\n"; }
  ~Logger() { std::cout#include <iostream> << "destroyed\n"; }
};

For an object on the stack, the destructor runs when the object goes out of scope:

void run() {
  Logger log;  // Prints "created".
}              // Prints "destroyed".

For an object allocated with new, the destructor runs when delete is called:

Logger* log = new Logger;  // Prints "created".
delete log;                // Prints "destroyed".

Destructors are used to release resources the object acquired, such as memory from new:

class Buffer {
public:
  Buffer() : data(new int[8]) {}
  ~Buffer() { delete[] data; }
  int* data;
};

void run() {
  Buffer buf;
}  // ~Buffer runs and internally frees data.

If no destructor is written, the compiler generates one that does nothing beyond destroying each field.