Pointer

Pointer is a variable that points toward a memory address. So a pointer is a data address. The data is somewhere else. Below picture will show you the relationship between a pointer and a data pointed by a pointer.

To declare a pointer, use the below statement :

Type

   PointerType : ^Type;

In this case, type can be an integer, a real, an array or record. And you can see the example code of using a pointer :

program Project1;
   {$APPTYPE CONSOLE}
uses
   SysUtils;

type
   PointerType = ^integer;

var
   MyPointer : PointerType;
   Data : integer;

begin
  Data := 100;
  MyPointer := @Data;
  writeln('Data pointed toward by the pointer is ', MyPointer^);
  Data := 123;
  writeln('Data pointed toward by the pointer is ', MyPointer^);
  readln;
end.

Disposing pointer allocation

To free the memory that is used by a pointer, you can use dispose statement.

  Dispose(pointer);

Example :

program Project1;
   {$APPTYPE CONSOLE}
uses
   SysUtils;

var
   MyPointer : ^integer;

begin
  New(MyPointer); // allocate memory
  MyPointer^ := 100;
  writeln('Vallue pointed toward by MyPointer is ',MyPointer^);
  Dispose(MyPointer); // free memory allocation
  readln;
end.

You can download the complete code here.