CONST - Revision history

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2013-02-08T13:07:07Z

Created page with "= <span class="f_Header">Action</span> = Declares a symbolic constant. <span style="font-family: Arial;"> </span> <span style="font-family: Arial;"> </span> = <s..."

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= <span class="f_Header">Action</span> =

Declares a symbolic constant.

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= <span class="f_Header">Syntax</span> =

<span class="f_Syntax">CONST</span> symbol = numconst

<span class="f_Syntax">CONST</span> symbol = stringconst

<span class="f_Syntax">CONST</span> symbol = expression

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= <span class="f_Header">Remarks</span> =
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{| width="567" cellspacing="0" cellpadding="1" border="1" style="border: 2px solid rgb(0, 0, 0); border-spacing: 0px; border-collapse: collapse;"
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Symbol

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The name of the symbol.

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Numconst

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The numeric value to assign to the symbol.

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Stringconst

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The string to assign to the symbol

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Expression

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An expression that returns a value to assign the constant

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Assigned constants consume no program memory because they only serve as a reference to the compiler.

The compiler will replace all occurrences of the symbol with the assigned value.

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You can use a constant to give a value a more meaningful name.

For example : variable = 1

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                 const optHeaterOn = 1

                 variable = optHeaterOn

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The source code is better to read when you assign a constant. Even better when the values change later, for example when HeaterOn becomes 2, you only need to replace 1 line of code.

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= <span class="f_Header">See also</span> =

[[ALIAS]]

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= <span class="f_Header">Example</span> =

<br/><source lang="bascomavr">
'-----------------------------------------------------------------------------------------
'name : const.bas
'copyright : (c) 1995-2005, MCS Electronics
'purpose : demo for constants
'micro : Mega48
'suited for demo : yes
'commercial addon needed : no
'-----------------------------------------------------------------------------------------

$regfile = "m48def.dat" ' specify the used micro
$crystal = 4000000 ' used crystal frequency
$baud = 19200 ' use baud rate
$hwstack = 32 ' default use 32 for the hardware stack
$swstack = 10 ' default use 10 for the SW stack
$framesize = 40 ' default use 40 for the frame space

'dimension some variables
Dim Z As String * 10
Dim B As Byte

'assign some constants
'constants dont use program memory
Const S = "test"
Const A = 5 'declare a as a constant
Const B1 = &B1001

'or use an expression to assign a constant
Const X =(b1 * 3) + 2
Const Ssingle = Sin(1)

Print X
Print Ssingle

B = A
'the same as b = 5

Z = S
'the same as Z = "test"

Print A
Print B1
Print S

'you can use constants with conditional compilation
#if A = 5 ' note there is no then
Print "constant a is 5"
#if S = "test"
Print "nested example"
#else ' else is optional
#endif
#else
#endif
End
</source><br/>{{Languages}}

[[Category:BASCOM Language Reference]]