Procedure: what changed

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

Title: Procedure

New		Line
1	+	A procedure is a [[Routine\|routine]] that does not return a value. `procedure` is a [[Reserved word\|reserved word]].
2	+
3	+	## Prematurely leaving a procedure
4	+
5	+	In a procedure the routine [`exit`](https://www.freepascal.org/docs-html/rtl/system/exit.html) can be called in order to (prematurely) leave the procedure. `exit` may not be supplied with any parameters, since procedures do not return any value, but [[Function\|functions]] do. Supplying a parameter to `exit` inside a procedure definition will yield the compile-time error “Error: Procedures cannot return a value”.
6	+
7	+	## Invocation
8	+
9	+	Procedure calls are statements. They may not appear in expressions, since they do not produce a value of any kind. The following example highlights all lines with procedure calls.
10	+
11	+	``` pascal
12	+	program procedureDemo(input, output, stderr);
13	+
14	+	var
15	+	x: longint;
16	+
17	+	procedure foo;
18	+	begin
19	+	exit;
20	+	inc(x);
21	+	end;
22	+
23	+	begin
24	+	x := 42;
25	+	foo;
26	+	writeLn(x);
27	+	end.
28	+	```
29	+
30	+	Note, that `foo` contains unreachable code (`inc(x)` is never executed because of the \[unconditional\] `exit`).
31	+
32	+	## See also
33	+
34	+	- [[Basic Pascal Tutorial/Chapter 4/Procedures\|Tutorial: procedures]]
35	+	- [§ “Procedure statements” in the Reference Guide](https://www.freepascal.org/docs-html/ref/refsu53.html)
36	+	- [§ “Procedural types” in the Reference Guide](https://www.freepascal.org/docs-html/ref/refse17.html)
37	+
38	+	---
39	+	From the Free Pascal wiki, page "Procedure", as it stood on 2023-01-25 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).

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