Teledyne-lecroy Protocol Analyzers File-Based Decoding User Manual Uživatelský manuál stáhnout pdf (Strana 11)

File-based Decoding User Manual Chapter 2: Values

LeCroy Corporation 5

2.2 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 characters

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 throughout 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 is not created,

but the global variable is changed. For example:

set Global = 10;

Function()

{

Global = "cat";

Local = 20;

}

creates a local variable called Local, which is only visible within the function Function.

Additionally, it changes the value of

Global to "cat", which is visible to all functions.

This also changes its value type from an integer to a string.

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Teledyne-lecroy Protocol Analyzers File-Based Decoding User Manual Uživatelský manuál Strana 11