User manual

5
CHAPTER 2
CATC Scripting Language for USB Values
result = null;
Variables
Variables are used to store information, or data, that can be modified. A variable
can be thought of as a container that holds a value.
All variables have names. Variable names must contain only alphanumeric charac-
ters and the underscore ( _ ) character, and they cannot begin with a number. Some
possible variable names are
x
_NewValue
name_2
A variable is created when it is assigned a value. Variables can be of any value type,
and can change type with re-assignment. Values are assigned using the assignment
operator ( = ). The name of the variable goes on the left side of the operator, and the
value goes on the right:
x=[1,2,3]
New_value = x
name2 = "Smith"
If a variable is referenced before it is assigned a value, it evaluates to null.
There are two types of variables: global and local.
Global Variables
Global variables are defined outside of the scope of functions. Defining global
variables requires the use of the keyword set. Global variables are visible through-
out a file (and all files that it includes).
set Global = 10;
If an assignment in a function has a global as a left-hand value, a variable will not
be created, but the global variable will be changed. For example
set Global = 10;
Function()
{
Global = "cat";
Local = 20;
}