Difference between revisions of "Constant"

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{{Constant}}
 
{{Constant}}
  
A '''constant''' is a variable that does not change, it has a final value.
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A '''constant''' is a [[Variable|variable]] that does not change, it has a final value.
  
Constants are defined in the [[Const#Const_Section|<code>const</code> section]] of a Free Pascal program. When a symbol is defined as constant, the [[Compiler|Free Pascal compiler]] can often do some optimizations to make the output code faster or smaller.
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Constants are defined in the [[Const#Const_Section|<code>const</code> section]] of a [[FPC|Free Pascal]] [[Program|program]]. When a symbol is defined as constant, the [[Compiler|Free Pascal compiler]] can often do some optimizations to make the output code faster or smaller.
  
  
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Logical truth values
 
Logical truth values
* <code>[[False|false]]</code>
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* [[False|<syntaxhighlight lang="pascal" enclose="none">false</syntaxhighlight>]]
* <code>[[True|true]]</code>
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* [[True|<syntaxhighlight lang="pascal" enclose="none">true</syntaxhighlight>]]
  
 
data type limits
 
data type limits
* <code>[[Nil|nil]]</code>: empty pointer value
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* [[Nil|<syntaxhighlight lang="pascal" enclose="none">nil</syntaxhighlight>]]: empty [[Pointer|pointer]] value
* <code>[[maxint]]</code>: largest possible <code>[[Integer|integer]]</code> value
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* [[maxint|<syntaxhighlight lang="pascal" enclose="none">maxint</syntaxhighlight>]]: largest possible [[Integer|<syntaxhighlight lang="pascal" enclose="none">integer</syntaxhighlight>]] value
  
  
The mathematical value [[Pi|π]] is realized as a function in <code>System.Pi</code>, so you may shadow (redefine) it on your own.
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The mathematical value [[Pi|π]] is realized as a function in {{Doc|package=RTL|unit=system|identifier=pi|text=<syntaxhighlight lang="pascal" enclose="none">system.pi</syntaxhighlight>}}.
  
== see also ==
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== See also ==
* <code>[[Const]]</code>
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* [[Const|<syntaxhighlight lang="pascal" enclose="none">const</syntaxhighlight>]]
 
* [[Constants]]
 
* [[Constants]]
 
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* [[Class constants]]
[[Category:Constants]]
 
[[Category:Pascal]]
 

Revision as of 07:15, 9 August 2020

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A constant is a variable that does not change, it has a final value.

Constants are defined in the const section of a Free Pascal program. When a symbol is defined as constant, the Free Pascal compiler can often do some optimizations to make the output code faster or smaller.


Some special Free Pascal constants are:

Logical truth values

data type limits


The mathematical value π is realized as a function in system.pi.

See also