Campbell CR6 Series, Operator'S Manual

Page: 194 / 690

Section 7. Installation
194
7.6.3.4 Using Variable Pointers
A pointer is the memory address of a variable. Use a pointer as a convenient way
to reference the memory location of a variable rather than referencing it by name.
This is useful in a Function() instruction function when parameters are local to the
function and changes to them have no effect on original arguments.
Define a pointer variable using the @ operator. For example:
PTR = @X
Use the ! operator to de-reference a pointer (return the value at the pointer). For
example:
!PTR = Myvar
Use the @ operatore to return the name of the variable stored in a memory
location. For example:
Name=(@)X
Pointer variables must be of type LONG and initialized by the @ operator, or a
variable out-of-bounds error will occur.
When a Function() function returns a pointer, apply the ! operator to the function
call, as shown in the following example:
Function ConstrainFunc(Value As Long,Low As Long,High As Long) As
Long
If !Value < !Low Then
Return Low
ElseIf !Value > !High Then
Return High
Else
Return Value
EndIf
EndFunction
‘Call within program
FuncFltRes = !ConstrainFunc(@FltVal,@FltLow,@FltHigh)
7.6.3.5 Declaring Arrays
Related Topics:
•
Declaring Arrays
(p. 194)
• VarOutOfBounds
(p. 563)
Multiple variables of the same root name can be declared. The resulting series of
like-named variables is called an array. An array is created by placing a suffix of
(x) on the variable name. X number of variables are created that differ in name
only by the incrementing number in the suffix. For example, the four statements
Public TempC1
Public TempC2
Public TempC3
Public TempC4