System.SizeOf Function

Returns the number of bytes occupied by a variable or type.

Pascal

function SizeOf(X): Integer;

C++

int SizeOf( X);

File

System

Description

Pass a Delphi variable reference to SizeOf to determine the number of bytes used to represent the variable. Pass a type identifier to SizeOf to determine the number of bytes used to represent instances of that type. SizeOf is useful for determining the amount of memory to specify for the FillChar, Move, or GetMem procedures.

SizeOf returns 0 when the argument is an untyped variable.

Delphi Examples:

Copy Code

{
This example fills a char array with characters and then
assigns the array to a text edit.
}
procedure TForm1.Button1Click(Sender: TObject);
var
  S: array[0..79] of AnsiChar;
begin
  { Set to all Xs }
  FillChar(S, SizeOf(S), Ord('X'));
  Edit1.Text := S;
end;

Copy Code

{
This example makes a record.  Reports the size of the reocrd,
fills it and reports the contents.
}
type
  CustRec = record
    Name: string[30];
    Phone: string[14];
  end;

procedure TForm1.Button1Click(Sender: TObject);
 var
  P: ^CustRec;
  size: Integer;
begin
  GetMem(P, SizeOf(CustRec));
  Canvas.TextOut(10, 10, 'The size of the record is ' + IntToStr(SizeOf(CustRec)));
  P.Name := 'a12345678901234567890123456789';
  P.Phone := '9,1,4085551212';
  Canvas.TextOut(10, 40, 'Name was assigned this string: ' + P.Name);
  Canvas.TextOut(10, 70, 'Phone was assigned this string: ' + P.Phone);
  size := SizeOf(CustRec);
  FreeMem (P, size);
end;