CONST

Action

Declares a symbolic constant.

 

 

Syntax

CONST symbol = numconst

CONST symbol = stringconst

CONST symbol = expression

 

 

Remarks

Symbol	The name of the symbol.
Numconst	The numeric value to assign to the symbol.
Stringconst	The string to assign to the symbol
Expression	An expression that returns a value to assign the constant

 

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.

 

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

For example : variable = 1

 

                 const optHeaterOn = 1

                 variable = optHeaterOn

 

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.

 

 

See also

ALIAS

 

 

Example

'-----------------------------------------------------------------------------------------
'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

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