====== Constants ======

Constants can be used to declare a constant value (a value that cannot be
changed) within the program.   This essentially allows a number to be
assigned a name, often improving readability and debugging of the source
code.

===== Const =====
The ''Const'' statement can be used to declare constants in Cubloc BASIC:

<code xbasic>
Const  PI  As  Single = 3.14159
Const  WRTTIME  As  Byte  = 10
Const  MSG1 As String = "ACCESS PORT"  
</code>

When the constant is not given a type, the compiler will find an appropriate
type for it as shown below:

<code xbasic>
Const  PI = 3.14159          ' Declare as SINGLE
Const  WRTTIME  = 10         ' Declare as Byte
Const  MYROOM  = 310         ' Declare as Integer since it’s over 255.
Const  MSG1 = "ACCESS PORT"  ' Declare as String
</code>

===== Con (Another CONST method) =====

The ''Con'' statement can be also used to declare constants as shown below:

<code xbasic>
PI      Con 3.14159         ' Declare as Single.
WRTTIME Con 10              ' Declare as Byte
MYROOM  Con 310             ' Declare as Integer
MSG1    Con "ACCESS PORT"   ' Declare as String
</code>

===== Constant Arrays =====

With constant arrays, the user is able to store a list of values before the
program begins.  A program requiring a large number of constant values
can be simplified as shown below:

<code xbasic>
Const Byte DATA1 = (31, 25, 102, 34, 1, 0, 0, 0, 0, 0, 65, 64, 34)
I = 0
A = DATA1(I)     ' Store 31 in A.
I = I + 1
A = DATA1(I)     ' Store 25 in A.
Const Byte DATA1 = ("CUBLOC SYSTEMS")
</code>

''String'' data can be stored in ''Byte'' constant arrays.  Each ''Byte'' contains the
ASCII code of each character in the ''String''.   In the example above, if ''DATA1(0)'' is read, the ASCII code of 'C' is returned.  Likewise if ''DATA1(1)'' is read, ASCII code of 'U' is returned.
''Integer'' and floating point (''Single'') numbers can also be stored in arrays
as shown below:

<code xbasic>
Const Integer DATA1 = (6000, 3000, 65500, 0, 3200)
Const Long DATA2 = (12345678, 356789, 165500, 0, 0)
Const Single DATA3 = (3.14, 0.12345, 1.5443, 0.0, 32.0)
</code>

For multiple-line  constant arrays, end each  line  with  a  comma, or an
underscore character as shown :

1)

<code xbasic>
Const Byte DATA1 = (31, 25, 102, 34, 1, 0, 0, 0, 0, 0, 65, 64, 34,
                      12, 123, 94, 200, 0, 123, 44, 39, 120, 239,
                      132, 13, 34, 20, 101, 123, 44, 39, 12, 39)
</code>

2)

<code xbasic>
Const Byte DATA2 = (31, 25, 102, 34, 1, 0, 65, 64, 34_
  , 101, 123, 44, 39, 12, 39)
</code>

Please make note of the following differences between arrays and constant
arrays.

|                   ^  Array                 ^  Constant Array        ^
^ Storage Location  | Data Memory (SRAM)     | Program Memory(FLASH)  |
^ When Allocated    | At Runtime             | When Downloaded        |
^ Can be Changed    | Yes                    | No                     |
^ Purpose           | Store changing values  | Store constant values  |
^ When Powered Off  | Lost                   | Retained               |

===== Demo =====
{{:cubloc:const:cublocconst.png?600|}}



===== String Constants =====

String constant arrays are deprecated.


See also [[:cubloc:define:|#define]].

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