Data type: what changed

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Title: Data type

New		Line
1	+	# General
2	+
3	+	This page provides an assortment of data types in Free Pascal.
4	+
5	+	A data type is a template for a [[Data field\|data field]].
6	+
7	+	The data type of a field defines how the compiler and processor interpret it's content.
8	+
9	+	The visibility of a [[Data field\|data field]] depends on the location of it's declaration.
10	+
11	+	# Integer types
12	+
13	+	## Unsigned types
14	+
15	+	[[Data field\|Data fields]] of unsigned integral types can only contain positive integral numbers.
16	+
17	+	- [[UInt8]] - Range: (0 .. 255)
18	+	- [[Byte]] - Range: (0 .. 255)
19	+	- [[UInt16]] - Range: (0 .. 65535)
20	+	- [[Word]] - Range: (0 .. 65535)
21	+	- [[NativeUInt]] - Range: depends on the processor type.
22	+	- [[DWord]] - is equivalent to Longword.
23	+	- [[Cardinal]] - is equivalent to Longword.
24	+	- [[UInt32]] - Range: (0 .. 4294967295)
25	+	- [[Longword]] - Range: (0 .. 4294967295)
26	+	- [[UInt64]] - Range: (0 .. 18446744073709551615)
27	+	- [[QWord]] - Range: (0 .. 18446744073709551615)
28	+
29	+	## Signed types
30	+
31	+	[[Data field\|Data fields]] of signed integral types can contain positive and negative integral numbers.
32	+
33	+	- [[Int8]] - Range: (-128 .. 127)
34	+	- [[Shortint\|ShortInt]] - Range: (-128 .. 127)
35	+	- [[Int16]] - Range: (-32768 .. 32767)
36	+	- [[Smallint\|SmallInt]] - Range: (-32768 .. 32767)
37	+	- [[Integer]] - Range: is equivalent either to Smallint or Longint (for 16 respectively 32 bit processors).
38	+	- [[Int32]] - Range: (-2147483648 .. 2147483647)
39	+	- [[NativeInt]] - Range: depends on the processor type.
40	+	- [[Longint\|LongInt]] - Range: (-2147483648 .. 2147483647)
41	+	- [[Int64]] - Range: (-9223372036854775808 .. 9223372036854775807)
42	+
43	+	# Floating-point types
44	+
45	+	[[Data field\|Data fields]] of a floating-point type can contain:
46	+
47	+	1. positive and negative integral numbers with possible round-off errors.
48	+	2. positive and negative floating-point numbers.
49	+
50	+	- [[Single]] - Range: (1.5E-45 .. 3.4E38)
51	+	- [[Real]] - Range: depends on the platform.
52	+	- [[Real48]] - Range: 2.9E-39 .. 1.7E38
53	+	- [[Double]] - Range: (5.0E-324 .. 1.7E308)
54	+	- [[Extended]] - Range: depends on the platform.
55	+	- [[Comp]] - Range: (-2E64+1 .. 2E63-1)
56	+	- [[Currency]] - Range: (-922337203685477.5808 .. 922337203685477.5807)
57	+
58	+	# Boolean types
59	+
60	+	[[Data field\|Data fields]] of boolean type contain truth values.
61	+
62	+	- [[Boolean]] - Range: (True, False), 8 Bit
63	+	- [[Bytebool\|ByteBool]] - Range: (True, False), 8 Bit
64	+	- [[Wordbool\|WordBool]] - Range: (True, False), 16 Bit
65	+	- [[Longbool\|LongBool]] - Range: (True, False), 32 Bit
66	+
67	+	# Enumeration types
68	+
69	+	[[Data field\|Data fields]] of an enumeration type are "lists" (enumerations...) of integral unsigned constants.
70	+
71	+	- [[Enum Type]] - Range: (integral data types)
72	+
73	+	# Char types
74	+
75	+	## Char types with single byte encoding
76	+
77	+	- [[Char]] - Constant length: 1 byte, representation: 1 character.
78	+	- [[Shortstring\|ShortString]] - Maxmimum length: 255 characters.
79	+	- [[String]] - Maxmimum length: Shortstring or Ansistring (depends in the used compiler switch).
80	+	- [[PChar]] - Pointer to a null-terminated string without length restriction.
81	+	- [[Ansistring\|AnsiString]] - No length restriction.
82	+	- [[Pansichar\|PAnsiChar]] - Pointer to a null-terminated string without length restriction.
83	+
84	+	See the overview of the different [[Character and string types\|character and string types]].
85	+
86	+	## Char types with multi byte encoding
87	+
88	+	(The encoding with 2 or 4 bytes is system dependent.\
89	+
90	+	- [[WideChar]] - Constant length: 2 or 4 bytes, representation: 1 character.
91	+	- [[Widestring\|WideString]] - No length restriction.
92	+	- [[Pwidechar\|PWideChar]] - Pointer to a null-terminated wide string without length restriction.
93	+	- [[Unicodechar\|UnicodeChar]] - Constant length: 2 or 4 bytes, representation: 1 character.
94	+	- [[Unicodestring\|UnicodeString]] - No length restriction.
95	+	- [[Punicodechar\|PUnicodeChar]] - Pointer to a null-terminated Unicode string without length restriction.
96	+
97	+	See the overview of the different [[Character and string types\|character and string types]].
98	+
99	+	# Variant types
100	+
101	+	- [[Variant]]
102	+	- [[Olevariant]]
103	+
104	+	# Constants
105	+
106	+	- Untyped constants
107	+	- [[Const]] - Only simple data types can be used.
108	+	- Typed constants
109	+	- [[Const]] - Simple data types as well as records and arrays can be used.
110	+	- Resource Strings
111	+	- [[Resourcestring]] - Used for localisation (not available in all compiler modes).
112	+
113	+	# Structural types
114	+
115	+	- [[Array]] - The size of the array depends on the type and the number of elements it contains.
116	+	- [[Record]] - A combination of multiple data types.
117	+	- [[Set]] - A set of elements of an ordinal type; the size depends on number of elements it contains.
118	+
119	+	# Subrange types
120	+
121	+	- [[subrange types]] are a subset of a base type.
122	+
123	+	# Pointer
124	+
125	+	- [[Pointer]] - The size depends on the processor type.
126	+
127	+	# Classes and objects
128	+
129	+	- [[Object]] - Developed under Turbo Pascal 5.5 for DOS and the precursor of class.
130	+	- [[Class]] - Developed under Delphi 1.0 for Windows and the successor of object.
131	+
132	+	# See also
133	+
134	+	- [[Pascal basics]]
135	+
136	+	---
137	+	From the Free Pascal wiki, page "Data type", as it stood on 2021-08-29 after a change by Mozi, 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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