Campbell CR800 Series, Руководство оператора

Страница: 124 / 598

Section 7. Installation
124
Inserting Comments
'This program example demonstrates the insertion of comments into a program. Comments are
'placed in two places: to occupy single lines, such as this explanation does, or to be
'placed after a statement.
'Declaration of variables starts here.
Public Start(6) 'Declare the start time array
BeginProg
EndProg
7.6.2.2.2 Conserving Program Memory
One or more of the following memory-saving techniques can be used on the rare
occasions when a program reaches memory limits:
• Declare variables as
DIM
instead of
Public
.
DIM
variables do not
require buffer memory for data retrieval.
•
Reduce arrays to the minimum size needed. Arrays save memory over
the use of scalars as there is less "meta-data" required per value.
However, as a rough approximation, 192000 (4 kB memory) or 87000 (2
kB memory) variables will fill available memory.
•
Use variable arrays with aliases instead of individual variables with
unique names. Aliases consume less memory than unique variable
names.
•
Confine string concatenation to DIM variables.
•
Dimension string variables only to the size required.
Read More More information on string variable-memory use and
conservation is available in
String Operations
(p. 303).
7.6.3 Programming Syntax
7.6.3.1 Program Statements
CRBasic programs are made up of a series of statements. Each statement
normally occupies one line of text in the program file. Statements consist of
instructions, variables, constants, expressions, or a combination of these.
"Instructions" are CRBasic commands. Normally, only one instruction is
included in a statement. However, some instructions, such as
If
and
Then
, are
allowed to be included in the same statement.
Lists of instructions and expression operators can be found in CRBasic Editor
Help
(p. 122).