destructor

The Class Destructor

A destructor is a special member function of a class that is executed whenever an object of it's class goes out of scope or whenever the delete expression is applied to a pointer to the object of that class.

A destructor will have exact same name as the class prefixed with a tilde (~) and it can neither return a value nor can it take any parameters. Destructor can be very useful for releasing resources before coming out of the program like closing files, releasing memories etc.

Following example explains the concept of destructor:

#include <iostream>
 
using namespace std;
 
class Line {
   public:
      void setLength( double len );
      double getLength( void );
      Line();   // This is the constructor declaration
      ~Line();  // This is the destructor: declaration
 
   private:
      double length;
};
 
// Member functions definitions including constructor
Line::Line(void) {
   cout << "Object is being created" << endl;
}

Line::~Line(void) {
   cout << "Object is being deleted" << endl;
}
 
void Line::setLength( double len ) {
   length = len;
}
 
double Line::getLength( void ) {
   return length;
}

// Main function for the program
int main( ) {
   Line line;
 
   // set line length
   line.setLength(6.0); 
   cout << "Length of line : " << line.getLength() <<endl;
 
   return 0;
}

When the above code is compiled and executed, it produces the following result:

Object is being created
Length of line : 6
Object is being deleted