Equal: what changed

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

Title: Equal

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1	+	<div style="float:right; margin: 0 10px 10px 0; padding:40px; font-size:500%; font-family: Georgia; background-color: #f9f9f9; border: 2px solid #777777;">
2	+
3	+	=
4	+
5	+	</div>
6	+
7	+	The symbol `=` (pronounced “equal”) is used to
8	+
9	+	- compare two (comparable) values for equality,
10	+	- [[Constant\|constant]] declarations (including [[Resourcestring\|resourcestring sections]]), and
11	+	- [[Type\|type declarations]], as well as
12	+	- specifying [[Default parameter\|default values]] for formal parameters in method declarations.
13	+
14	+	Furthermore, if [[Enum Type\|enumeration data types]] are defined with explicit indices, [[FPC]]’s Delphi compatibility modes require an equal sign instead of [[Becomes\|:=]] when specifying the indices.
15	+
16	+	## application
17	+
18	+	``` pascal
19	+	program equalDemo(input, output, stderr);
20	+
21	+	const
22	+	answer = 42;
23	+
24	+	resourcestring
25	+	prompt = 'What''s the answer?';
26	+
27	+	type
28	+	number = longint;
29	+
30	+	var
31	+	i: number;
32	+
33	+	begin
34	+	writeLn(prompt);
35	+	readLn(i);
36	+
37	+	if not (i = answer) then
38	+	begin
39	+	exitCode := 1;
40	+	end;
41	+	end.
42	+	```
43	+
44	+	Be aware of what you compare: When you compare two references, i.e. [[Class\|class]] or [[Pointer\|pointer]] variables, without dereferencing them first, you usually compare two memory addresses, not the actual content at those addresses. Operator overloading may alter this behavior, though. For instance the content of [[Ansistring\|ansistrings]] can be compared without any special treatment, though internally (transparently) they are realized as pointers.
45	+
46	+	Note, you usually do not use the equal sign comparison in conjunction with [[IEEE 754 formats\|floating-point numbers]]. Instead one uses [`math.compareValue`](https://www.freepascal.org/docs-html/rtl/math/comparevalue.html).
47	+
48	+	## comparitive remarks
49	+
50	+	Unlike other programming languages, the symbol is not used to assign a value, for that the character pair [[Becomes\|:=]] is used. An exception of this are “initialized variables”, where you specify an initial value inside the [[Var\|var section]] alongside your [[Variable\|variable]] declarations:
51	+
52	+	``` pascal
53	+	program initializedVariable(input, output, stderr);
54	+
55	+	var
56	+	i: longint;
57	+	response: string = 'Wrong!';
58	+
59	+	begin
60	+	writeLn('What''s the answer?');
61	+	readLn(i);
62	+
63	+	if i = 42 then
64	+	begin
65	+	response := 'Right!';
66	+	end;
67	+
68	+	writeLn(response);
69	+	end.
70	+	```
71	+
72	+	Also, a comparison always results in a [[Boolean\|boolean value]].
73	+
74	+	## ASCII value
75	+
76	+	In [[ASCII]], the character code decimal `61` (or [[Hexadecimal\|hexadecimal]] `3D`) is defined to be `=` (equals sign).
77	+
78	+	## see also
79	+
80	+	- [[Becomes\|becomes-operator :=]] assigns values to a variable
81	+	- [[Not equal\|not-equal-operator <>]] checks for inequality
82	+
83	+	---
84	+	From the Free Pascal wiki, page "Equal", as it stood on 2020-11-10 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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