NetLinx Programming Overview
14
NetLinx Programming Language Reference Guide
NetLinx expands the capabilities of the assignment operator '=' to support arrays. Similar array levels are
assigned to another array using the '
=' operator, if the arrays match the number of dimensions and the
data type of the array. You cannot assign a two-dimensional long array to a one-dimensional character
array. The
MAX_LENGTH_ARRAY of the array to the left of the '=' operator must be greater than or equal
to the
LENGTH_ARRAY of the array to the right of the '=' operator.
INTEGER ARRAY1[10] = {1, 2, 3, 4}
INTEGER ARRAY2[10] = {5, 6, 7}
INTEGER ARRAY3[10]
INTEGER DIM2ARRAY1[3][4] = { {1, 2, 3}, {4, 5, 6} }
INTEGER DIM2ARRAY2[3][4] = { {7, 8, 9} }
INTEGER DIM2ARRAY3[3][4]
ARRAY3 = ARRAY1 (* ARRAY3 = {1, 2, 3, 4} *)
DIM2ARRAY2[2] = ARRAY1 (* DIM2ARRAY2 = { {7, 8, 9}, {1, 2, 3, 4} } *)
DIM2ARRAY3 = DIM2ARRAY1 (* DIM2ARRAY3 = { {1, 2, 3}, {4, 5, 6} } *)
Structures
Arrays are limited by their inability to have multiple data-types within one array. NetLinx supports
Structures to remove this limitation. Structures group different data types together as one data unit.
Structures also group arrays of structures together so that each element of the array contains all of the
elements of the structure. This may sound complex, but it is actually very familiar.
A database table is an array of structures. The database table is an array of records. Each record is a
structure. Each record contains data of different types. Let's first consider the elements of a database
table. We then show how to define the structure and create a variable that uses the data structure in an
array. We show how to access the individual elements of the structure.
Employee Number (* INDEX - Integer Value *)
Employee National Insurance Number (* National Insurance Number - Long *)
Employee First Name (* First Name - Character Array *)
Employee Last Name (* Last Name - Character Array *)
Contribution to Pension (* Contribution in % - Float *)
The DEFINE_TYPE section is added to the basic structure of a NetLinx Program. Structures are defined
within the
DEFINE_TYPE section. The DEFINE_TYPE section appears between the
DEFINE_CONSTANT section and the DEFINE_VARIABLE section. Since structures cannot be used
within the
DEFINE_CONSTANT section but must be declared before they are used within the
DEFINE_VARIABLE section, placing DEFINE_TYPE between DEFINE_CONSTANT and
DEFINE_VARIABLE is the logical location.
The attributes
NON_VOLATILE, VOLATILE, and CONSTANT do not apply to the individual data
elements of the structure, but can be attributed to the instances of the structure as defined in the
DEFINE_VARIABLE section.
The standard format for structures is:
STRUCTURE <name>
{
[<type>] <data1>
[<type>] <data2>
.
.
}
Using this format, we define our 'employee' structure in the DEFINE_TYPE section:
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