Available on: all targets
Alias: SHARED CONST CONST SHARED GLOBAL CONST CONST GLOBAL

CONST

Using the CONST command allows you to define one or more constants, which will be used later in the program. Constants have the advantage of being calculated once and for all, at compile time, directly by the compiler and can be used to initialize variables. Furthermore, the constants are global, that is, they are always visible everywhere, both in the main program and within the procedures. Finally, constants do not take up memory space.

In the definition of the constants itself it is possible to indicate whether it must be positive or not, with the keyword POSITIVE. This check is carried out at compilation time and, in the event of a negative result, it will result in a compilation error. This condition is useful to ensure that the preconditions related to the hardware are respected (as happens, for example, when calculating the margins in the case of a screen smaller than the expected minimum).

It is also possible to define a validity range of the values that will be represented in the constant. This interval is defined in a similar way to intervals in mathematics: using the square bracket means that the extremes (minimum, maximum) are included, while a round bracket means that the extremes are excluded.

syntax example abbreviation back to keywords

SYNTAX

 [POSITIVE] CONST identifier = value
 CONST identifier IN (min,max) = value
 CONST identifier IN "[" min,max) = value
 CONST identifier IN (min,max "]" = value
 CONST identifier IN "[" min,max "]"" = value


Legend
  • id : identifier
  • type : datatype
  • v : value
  • "..." : string
  • [...] : optional

EXAMPLE

 CONST x = 42
 POSITIVE CONST y = -42: ' this raises an error!
 CONST width IN (0,320] = 128


Used in:

ABBREVIATION: C#

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In order to reduce space you can use this abbreviation for this instruction: 

CONST ↔ C#

Any problem?

If you have found a problem with this keyword, if you think there is a bug or, more simply, you would like it to be improved, open an issue for this example on GitHub.
Thank you!

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