10. Getting information

• 
      size_type size() const;
  
      bool empty() const;
  
      size_type capacity() const;
  
  

• You can use resize( ) to change the size of a vector.

• If it gets longer, the new elements are initialized with the second argument.

  
      void resize( size_type n, T x = T() );
  
  

• reserve( ) does the same thing for capacity,

  • but without any initialization. Current content is preserved.

  
      void reserve( size_type n );