Difference between revisions of "Real"
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{{Real}} | {{Real}} | ||
− | + | <syntaxhighlight lang="pascal" inline>real</syntaxhighlight> is a [[Standard type|standard type]] of the [[Pascal]] programming language. | |
− | + | == usage == | |
+ | Floating-point literals can be assigned to <syntaxhighlight lang="pascal" inline>real</syntaxhighlight> variables. | ||
+ | <syntaxhighlight lang="pascal" line> | ||
+ | program realDemo(input, output, stderr); | ||
− | + | var | |
+ | r: real; | ||
− | + | begin | |
− | + | r := 0.; // r becomes zero | |
− | + | writeLn(r, ' ', r:8:4); | |
− | + | ||
+ | r := 1e2; // r becomes 1*(10^2) [a hundred] | ||
+ | writeLn(r, ' ', r:8:4); | ||
+ | |||
+ | r := r / r; // r becomes one | ||
+ | writeLn(r, ' ', r:8:4); | ||
+ | end. | ||
+ | </syntaxhighlight> | ||
+ | <syntaxhighlight lang="pascal" inline>real</syntaxhighlight>, like all floating-point types, supports [[Slash#division|<syntaxhighlight lang="pascal" inline>/</syntaxhighlight> division operator]], while integer types support <syntaxhighlight lang="pascal" inline>div</syntaxhighlight>-operator. | ||
− | + | == internal representation == | |
− | + | The internal representation of the type <syntaxhighlight lang="pascal" inline>real</syntaxhighlight> (i.e. number of bytes and byte ordering) and the resulting range and precision are platform dependent. | |
− | + | Quote from the “FreePascal Programmer's Manual” (Chapter 8.2.5 [https://www.freepascal.org/docs-html/prog/progsu158.html Floating point types]): | |
+ | <blockquote> | ||
+ | Contrary to Turbo Pascal, where the <syntaxhighlight lang="pascal" inline>real</syntaxhighlight> type had a special internal format, under Free Pascal the <syntaxhighlight lang="pascal" inline>real</syntaxhighlight> type simply maps to one of the other real types. | ||
+ | It maps to the [[Double|<syntaxhighlight lang="pascal" inline>double</syntaxhighlight> type]] on processors which support floating point operations, while it maps to the [[Single|<syntaxhighlight lang="pascal" inline>single</syntaxhighlight> type]] on processors which do not support floating point operations in hardware. | ||
+ | </blockquote> | ||
+ | |||
+ | == alternatives == | ||
+ | Instead of specifying <syntaxhighlight lang="pascal" inline>real</syntaxhighlight> in your code, write {{Doc|package=RTL|unit=system|identifier=valreal|text=<syntaxhighlight lang="pascal" inline>ValReal</syntaxhighlight>}}, a type alias defined by the [[System unit]]. | ||
+ | It automatically maps to the largest available floating point type available: <syntaxhighlight lang="pascal" inline>single</syntaxhighlight>, <syntaxhighlight lang="pascal" inline>double</syntaxhighlight> or <syntaxhighlight lang="pascal" inline>extended</syntaxhighlight>. | ||
{{Data types}} | {{Data types}} |
Revision as of 17:36, 6 March 2022
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real
is a standard type of the Pascal programming language.
usage
Floating-point literals can be assigned to real
variables.
1program realDemo(input, output, stderr);
2
3var
4 r: real;
5
6begin
7 r := 0.; // r becomes zero
8 writeLn(r, ' ', r:8:4);
9
10 r := 1e2; // r becomes 1*(10^2) [a hundred]
11 writeLn(r, ' ', r:8:4);
12
13 r := r / r; // r becomes one
14 writeLn(r, ' ', r:8:4);
15end.
real
, like all floating-point types, supports /
division operator, while integer types support div
-operator.
internal representation
The internal representation of the type real
(i.e. number of bytes and byte ordering) and the resulting range and precision are platform dependent.
Quote from the “FreePascal Programmer's Manual” (Chapter 8.2.5 Floating point types):
Contrary to Turbo Pascal, where the
real
type had a special internal format, under Free Pascal thereal
type simply maps to one of the other real types. It maps to thedouble
type on processors which support floating point operations, while it maps to thesingle
type on processors which do not support floating point operations in hardware.
alternatives
Instead of specifying real
in your code, write ValReal
, a type alias defined by the System unit.
It automatically maps to the largest available floating point type available: single
, double
or extended
.
simple data types |
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complex data types |