Hi

I remember there is a way to get a string representation of an enumerated type directly without using a lookup string array, but I forgot the syntax. Lazarus uses only lookup arrays, maybe because the other syntax is new.

How is the syntax?

Juha

One option is RTTI:

http://wiki.lazarus.freepascal.org/Runtime_Type_Information_(RTTI)#Converting_a_enumerated_type_to_a_string

You can directly write enums with Write or WriteLn and convert enums to strings with WriteStr.

program EnumStr;
{$mode objfpc}{$H+}
type
  TColor = (cRed, cGreen, cBlue, cYellow);
function ColorToStr(C: TColor) : String;
begin
  WriteStr(Result, C);
end;
var
  Color : TColor;
begin
  for Color in TColor do
    WriteLn(ColorToStr(Color));
end.

2011/11/1 Juha Manninen :

On Tue, November 1, 2011 08:41, Juha Manninen wrote:

Hi,

type
 TNum = (One, Two, Three);
var
 N: TNum;
 S: string;
begin
 N := One;
 WriteLn (N);
 N := Two;
 WriteStr (S, N);
 WriteLn (S);
end.

Tomas

Hi,

This is code I wrote for converting 1, 2 or 3 digit numbers to string.

	function NumtoString(N:integer):string;
	var
		c1, c2, c3: char;
	begin
		if (N<10) then
			NumtoString := chr(N+48)
		else if (N > 9) and (N < 100) then
			begin
				c1 := chr((N div 10) + 48);
				c2 := chr((N mod 10) + 48);
				NumtoString := concat(c1, c2);
			end
		else if (N > 99) and (N < 1000) then
			begin
				c1 := chr((N div 100) + 48);
				c2 := chr((N mod 100) div 10 + 48);
				c3 := chr((N mod 10) + 48);
				NumtoString := concat(c1, c2, c3);
			end;
	end;

Thomas Young
cell: 330-256-7064
mobile email:

WriteStr (S, N);

Thanks guys!
WriteStr() was the function I was looking for.
I found some places in Lazarus code where it is used but not many. Martin's debugger code has some.
I think many lookup string arrays in Lazarus code could be replaces with WriteStr. It would reduce code size and improve code maintenance.

If I understand right WriteStr uses RTTI internally. So, every enum type already carries the string explicit lookup
array is duplicate data.

Juha

2011/11/1 Juha Manninen :

It is a relatively new feature, since fpc 2.4.0 IIRC.

Vincent

You can also use the plain str() procedure.

Jonas

Not really, if rtti for a certain enum is never used, the linker won't include it.