c++ - Is setting pointer to null an allocated memory? -

i reading code initializes pointer null, thought code not allocating new memory pointer storing 2d array of values (which does) made me wonder, pointer initialized null pointer allocated memory?

class int8_tset : public gridset { public:   int8_t** set; // //   int8_tset():set(0) {}   int8_tset( const int8_tset& x ):set(0) {copy(x);}   virtual ~int8_tset() { free2darray(set);} // // --- opeartor   int8_t  operator() ( intvector2d x ) const {return set[x.i][x.j];}   int8_t& operator() ( intvector2d x ) {return set[x.i][x.j];} // --- function   void set();   void set(int8_t val);   void set( intvector2d x ){ ns_griddata::set(x,*this,(int8_t)-1); }   void set( intvector2d x,int8_t val){ ns_griddata::set(x,*this,val); }   void switch(); // --- output & input   void output(std::ostream& out ) const;   void input (std::istream& in  ); // --- copy & substitute public:   void copy( const int8_tset& x ) {ns_griddata::copy(*this,x,(int8_t) -1);}   const int8_tset& operator = ( const int8_tset& x );    void extract(intvector2d &ll, intvector2d &ur,int8_tset &subgrid) const; };   void int8_tset::set() {   if(!set) {std::cerr<<" memory not allocated. call set(x) first \n"; exit(1); }   std::fill(set[0],set[0]+size.i*size.j,-1); } 

i realized allocating memory in void set.

is pointer initialized null pointer allocated memory

i guess mean like:

type* ptr = null; 

in case memory allocated pointer (about variable ptr) - sizeof(type*).
but not point allocated memory, delete ptr; not necessary (but still safe).