Constants are identifiers that represent literals or constant expressions that can not be changed after they are defined.
For example,
Const PI = 3.1415926535897932 will always mean that the identifier
PI refers to the number
3.1415926535897932. The identifier
PI can be used instead of repeating the full number in source.
Global constants once defined, are available globally and the identifier can be used to refer to the constant anywhere in the source program.
After an identifier is defined with the
Const statement, the symbol cannot be altered. If code tries to alter a constant, an error message will result upon code compilation.
Built-in constants include the
Boolean data type values
True and
False.
A constant definition differs from a variable definition. Variables hold values that can be changed.
Example
Declare Sub PrintConstants ()
Const FirstNumber = 1
Const SecondNumber = 2
Const FirstString = "First string."
Const FirstBoolean = False
Const SecondBoolean = True
Print FirstNumber, SecondNumber 'This will print 1 2
Print FirstString 'This will print First string.
Print FirstBoolean, SecondBoolean 'This will print false true
Print
PrintConstants ()
Sub PrintConstants ()
Print FirstNumber, SecondNumber 'This will also print 1 2
Print FirstString 'This will also print First string.
Print FirstBoolean, SecondBoolean 'This will also print false true
End Sub
See also