Special Member Functions

• Some member functions are special.
  • They concern the management of objects.
  • Their names are related to the class’s name.
  • The compiler will automatically insert calls to these member functions when needed.
  • In some classes, the compiler will create them for us.
• In traditional C++, these member functions are…
  1. Constructor
  2. Copy Constructor
  3. Assignment Operator
  4. Destructor

Constructor

• Has the same name as the class.
• Initializes a newly created object using its arguments.
• Performs any initial configuration required.

  // init object from arguments
  Test(int i, const string& str): i(i), str(str) {
    // allocate memory, connect to the db, etc...
  }

Copy Constructor

• Similar to constructor, but uses another object for initialization.
  • Always takes one argument.
    • A reference to another object of the same class.

  // init object from another Test object
  Test(const Test& other): i(other.i), str(other.str) {
    // do stuff
  }

Assignment Operator

• Assigns an existing object from another object
• Always takes one argument:
  • A reference to another object of the same class.
• Returns a reference to the assigned object:
  • Should be a non-const reference, for consistency with built in types.

  // Assign object from another Test object
  Test& operator = (const Test& other) {
    i = other.i;
    str = other.str;
    return *this;
  }

Destructor

• Called before the class members are released in memory.
• Performs any tidying-up required before the object is destroyed.

  // Prepare object to be released
  ~Test() {
    // release allocated memory, disconnect from db, etc...
  }