Difference between revisions of "Constant"

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{{Constant}}
 
{{Constant}}
  
A '''constant''' is a variable that does not change, it has a fixed value.
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A '''constant''' is a variable that does not change, it has a final value.
  
Constants are defined in the [[Const#Const_Section|const]] section of a Free Pascal program. When a variable is 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 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.
  
Some special Free Pascal constants:
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Some special Free Pascal constants are:
  
 
Logical truth values
 
Logical truth values
* [[False]]
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* <code>[[False|false]]</code>
* [[True]]
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* <code>[[True|true]]</code>
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data type limits
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* <code>[[Nil|nil]]</code>: empty pointer value
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* <code>[[Maxint|maxint]]</code>: largest possible <code>[[Integer|integer]]</code> value
  
Empty pointer value
 
* [[Nil]]
 
  
Mathematical values
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The mathematical value [[Pi]] is realized as a function in <code>System.Pi</code>, so you may shadow (redefine) it on your own.
* [[Pi]]
 
  
== read more ==
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== see also ==
* [[Const]]
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* <code>[[Const]]</code>
 
* [[Constants]]
 
* [[Constants]]
  
 
[[Category:Constants]]
 
[[Category:Constants]]
 
[[Category:Pascal]]
 
[[Category:Pascal]]

Revision as of 13:26, 24 January 2018

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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, so you may shadow (redefine) it on your own.

see also