On: what changed

Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.

Title: On

New		Line
1	+	Back to [[Reserved words]].
2	+
3	+	The `on` [[Keyword\|keyword]] to act on the [[Exceptions\|exception]] type. The `on` clause checks against one of a number of exception classes.
4	+
5	+	``` pascal
6	+
7	+	try
8	+	//guarded block of code
9	+	// ...
10	+	except
11	+	on {exception type} do begin
12	+	//exception block-handles SomeException
13	+	end;
14	+	end;
15	+
16	+	```
17	+
18	+	``` pascal
19	+
20	+	program range_error;
21	+	{$mode objfpc} {$H+}
22	+	{$R+} // Range check on
23	+	uses sysutils;
24	+	var
25	+	i,j:integer;
26	+	arr:array[0..9] of integer;
27	+	begin
28	+	try
29	+	i := 0;
30	+	j := 10;
31	+	while i < j do
32	+	begin
33	+	inc(i);
34	+	arr[i] := i + j;
35	+	WriteLn( i,' ', arr[i]);
36	+	end;
37	+	except
38	+	on E:ERangeError do begin
39	+	WriteLn('Error: valid range exceeded detected.');
40	+	WriteLn(E.Message);
41	+	end;
42	+	on E:Exception do // generic handler
43	+	WriteLn('Caught ' + E.ClassName + ': ' + E.Message);
44	+	end;
45	+	WriteLn('Press any key');
46	+	ReadLn;
47	+	end.
48	+	```
49	+
50	+	## See also
51	+
52	+	- [[Try]]
53	+	- [[Except]]
54	+
55	+	---
56	+	From the Free Pascal wiki, page "On", as it stood on 2022-08-06 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).