Malvern Instruments Zetasizer 1000, Основное руководство пользователя

Страница: 20 / 123

There is space for 50 user variables in any program. An error is reported if this number is
exceeded. If one program calls another the variables in the calling program are not accessible
from the called program (but see below for arrays).
It is good practice to choose variable names which describe the values they will contain. This
‘self-documenting’ approach together with comments will make program maintenance and
debugging much easier.
Certain names will be disallowed. You cannot use a command or function name as a variable
name.
The names of string (text) variables follows the convention of numeric variables but the names
must end with a $ (dollar symbol).
String arrays are not allowed. The total number of numeric,
array and string variables must not exceed 50 per program. The maximum length of strings must
be less than 256 characters.
Unlike some versions of Basic, the Zetasizer Basic does not require you to declare all variables
explicitly before use.
A numeric or string variable is recognized the first time a value is assigned
to it. However arrays must be declared before use.
2.5 Arrays
An array is a group of values referred to by a single name. The individual values in the array are
referred to by an index number.
For example MyData could be an array of 6 elements which would be referenced as MyData(0),
MyData(1), MyData(2), ... , MyData(5).
Notice that the numbering of the array is assumed to start at zero. If it is convenient for clarity to
use only the elements from number 1 onwards you can, of course, ignore element 0.
Unlike simple variables, it is necessary to declare arrays before they are used so that memory
can be reserved for them.
This is done using the Dim command.
Array names follow the same rules as for simple variables. String arrays are not allowed. All
arrays are one-dimensional. That is arrays of the type X ( 3, 5 ) are not allowed.
For example :
Dim Ax ( 10 ), Ay ( 10 ), Big_List ( 1000 )
The dimension of an array is limited to 1000 (i.e. 1001 elements).
In a Dim command you may use variables and functions to specify the array sizes.
For example:
X = 10
Dim A ( 2 * X + 1 )
Dim B ( StoreChannel )
are valid.
Once an array is dimensioned you may not change its dimension.
MAN0179
Page 2.4 Zetasizer 1000/2000/3000/4000/5000/4700
Artisan Scientific - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisan-scientific.com