System.Ptr Function

Converts a specified address to a pointer.

Pascal

function Ptr(Address: Integer): Pointer;

C++

void * Ptr(int Address);

File

System

Description

In Delphi code, Ptr converts the given Address to a pointer. A call to this function generates no code, but simply treats the 32-bit value given by Address as a pointer. Like nil, the result of Ptr is assignment compatible with all pointer types.

Delphi Examples:

Copy Code

{
The following code demostrates the use of Ptr function. The example
makes use of Ptr to simulate pointer arithmetics.
}
function FastUpperCase(const S: String): String;
var
  C: ^Char;
  I: Integer;
begin
  { Get the text in the edit box }
  Result := S;

  { Ensure the string reference stored in Result is unique,
    otherwise we may change the original string also.
    No copy-on-write is done if we're accesing the character
    directly.
  }
  UniqueString(Result);

  { Find the address of the first char in the string }
  C := Addr(Result[1]);

  for I := 0 to Length(Result) - 1 do
  begin
    { Up-case the character }
    C^ := UpCase(C^);

    { Move to the next character }
    C := Ptr(Integer(C) + SizeOf(Char));
  end;
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
  { Uppercase the string in the edit box }
  Edit1.Text := FastUpperCase(Edit1.Text);
end;