3. std::set

• A set is a container that holds unique elements.

• The elements in std::set are always sorted.

  
      #include <cassert>
      #include <iostream>
      #include <set>
      using namespace std;
      int main (int argc, char* argv[])
      {
          set< int > iset;   // set of unique integer numbers
  
          iset.insert( 11 ); // populate set with some values
          iset.insert( -11 );
          iset.insert( 55 );
          iset.insert( 22 );
          iset.insert( 22 );
          if ( iset.find( 55 ) != iset.end() ) { // is value already stored?
              iset.insert( 55 );
          }
          assert( iset.size() == 4 ); // sanity check :-)
          set< int >::iterator it;
          for ( it = iset.begin(); it != iset.end(); it++ ) {
              cout << " " << *it;
          }
          return 0;
      }
      // Output:  -11 11 22 55