Equal: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

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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	1		=
4		-
5		-	~~</div>~~
6	2
7	3		The symbol `=` (pronounced “equal”) is used to
8	4
9	5		- compare two (comparable) values for equality,
10	6		- [[Constant\|constant]] declarations (including [[Resourcestring\|resourcestring sections]]), and
11	7		- [[Type\|type declarations]], as well as
12	8		- specifying [[Default parameter\|default values]] for formal parameters in method declarations.
13	9
14	10		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	11
16	12		## application
17	13
18	14		``` pascal
19	15		program equalDemo(input, output, stderr);
20	16
21	17		const
22	18		answer = 42;
23	19
24	20		resourcestring
25	21		prompt = 'What''s the answer?';
26	22
27	23		type
28	24		number = longint;
29	25
30	26		var
31	27		i: number;
32	28
33	29		begin
34	30		writeLn(prompt);
35	31		readLn(i);
36	32
37	33		if not (i = answer) then
38	34		begin
39	35		exitCode := 1;
40	36		end;
41	37		end.
42	38		```
43	39
44	40		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	41
46	42		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	43
48	44		## comparitive remarks
49	45
50	46		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	47
52	48		``` pascal
53	49		program initializedVariable(input, output, stderr);
54	50
55	51		var
56	52		i: longint;
57	53		response: string = 'Wrong!';
58	54
59	55		begin
60	56		writeLn('What''s the answer?');
61	57		readLn(i);
62	58
63	59		if i = 42 then
64	60		begin
65	61		response := 'Right!';
66	62		end;
67	63
68	64		writeLn(response);
69	65		end.
70	66		```
71	67
72	68		Also, a comparison always results in a [[Boolean\|boolean value]].
73	69
74	70		## ASCII value
75	71
76	72		In [[ASCII]], the character code decimal `61` (or [[Hexadecimal\|hexadecimal]] `3D`) is defined to be `=` (equals sign).
77	73
78	74		## see also
79	75
80	76		- [[Becomes\|becomes-operator :=]] assigns values to a variable
81	77		- [[Not equal\|not-equal-operator <>]] checks for inequality
82	78
83	79		---
84	80		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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