Table of Contents
Constants can be provided within a program in two ways. They can either be literal values or named constants.
The best example of a named constant always seems to be PI. It is a constant value although, because it has a large, possibly infinite number of decimal places, it is usually limited to only a few of those. PI can be variously defined as 3.142, 3.14159265 or to a value with even greater accuracy. It can even be defined as 22/7 for simple calculations. However we define it PI itself is still a constant value.
In the LynPlex interpreter constants are defined as:
const PI = 3.14159265
Note: In LynPlexS this would be defined as:
$$pi = 3.14159265
and in LynPlexC as:
const PI [as datatype] = 3.14159265
Assigning a name to a constant value means that you do not have to remember what the actual value is. For example:
c = 2 * PI * r
Constants in Expressions
Constants may be used anywhere in an expression. For example.
put "The value of PI is" PI
The value of PI is 3.14159265
Although constants are intended to remain the same throughout the program, the primary purpose of defining a value as a constant is to stop it being accidentally modified.
Having defined PI as shown above, the statement:
PI = 123456
will be rejected.
If you really want to, you can change any constant value provided that you redefine it as a constant. For example, if you want PI to have a lower precision enter:
const PI = 3.142
const PI = 22/7