“Destructor” functions are the inverse of constructor functions. They are called when objects are destroyed (deallocated). Designate a function as a class's destructor by preceding the class name with a tilde (~). For example, the destructor for class String is declared: ~String().
The destructor is commonly used to “clean up” when an object is no longer necessary. Consider the following declaration of a String class:
#include <string.h>
class String
{
public:
String( char *ch ); // Declare constructor
~String(); // and destructor.
private:
char *_text;
};
// Define the constructor.
String::String( char *ch )
{
// Dynamically allocate the correct amount of memory.
_text = new char[strlen( ch ) + 1];
// If the allocation succeeds, copy the initialization string.
if( _text )
strcpy( _text, ch );
}
// Define the destructor.
String::~String()
{
// Deallocate the memory that was previously reserved
// for this string.
delete[] _text;
}
In the preceding example, the destructor String::~String uses the delete operator to deallocate the space dynamically allocated for text storage.