cppreference.com > C++ Strings > resize resize Syntax:
      #include <string>
      void resize( size_type num, const TYPE& val = TYPE() );
The function resize() changes the size of the string to size. If val is specified then any newly-created elements will be initialized to have a value of val. This function runs in linear time. Related topics: (C++ Multimaps) Container constructors & destructors capacity size