(C++) Constructor

The method called when a class is instanciated. A class can have multiple constructors. The opposite of a constructor is a destructor.

class Example
{
  public:
  Example() 
    : mValue(0)
  {
    //Empty, as mValue is already set to zero
  }
  Example(const int& value) //Constructor #2
    : mValue(value); 
  {
    //Empty, as mValue is already set to value
  }
  const int mValue;
};
int main()
{
  Example e1;     //Calls constructor #1
  Example e2(10); //Calls constructor #2
  Example * pe1 = new Example;     //Calls constructor #1
  Example * pe2 = new Example(10); //Calls constructor #2
  delete pe1; //Calls destructor
  delete pe2; //Calls destructor
}

Define and initialize member variables in the same order [1]. Prefer initialization to assignment in constructors [2]. Never call virtual functions during construction or destruction [3,4].

Code links

References

1) Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Item 47: 'Define and initialize member variables in the same order'.
2) Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Item 48: 'Prefer initialization to assignment in constructors'
3) Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Item 49: 'Never call virtual functions during construction or destruction'
4) Scott Meyers. Effective C++ (3rd edition).ISBN: 0-321-33487-6. Item 9: Never call virtual functions during construction or destruction.

last edited (November 11, 2006) by bilderbikkel, Number of views: 6033, Current Rev: 5 (Diff)

[Edit this page] [Page history] [What links here] [Discuss this topic] [Printer Friendly]