Map Constructors & Destructors

  #include <map>
  map();
  map( const map& m );
  map( iterator start, iterator end );
  map( iterator start, iterator end, const key_compare& cmp );
  map( const key_compare& cmp );
  ~map();

The default constructor takes no arguments, creates a new instance of that map, and runs in constant time. The default copy constructor runs in linear time and can be used to create a new map that is a copy of the given map m.

You can also create a map that will contain a copy of the elements between start and end, or specify a comparison function cmp.

The default destructor is called when the map should be destroyed.

For example, the following code creates a map that associates a string with an integer:

  struct strCmp {
    bool operator()( const char* s1, const char* s2 ) const {
      return strcmp( s1, s2 ) < 0;
    }
  };

  ...

  map<const char*, int, strCmp> ages;
  ages["Homer"] = 38;
  ages["Marge"] = 37;
  ages["Lisa"] = 8;
  ages["Maggie"] = 1;
  ages["Bart"] = 11;

  cout << "Bart is " << ages["Bart"] << " years old" << endl;