TAL Programmer's Guide

Accessing Structure Items

Using Structures

8–28 096254 Tandem Computers Incorporated

Indexing Structures You can access a particular structure item by appending indexes (enclosed in brackets)

to the various levels in the qualified identifier of the structure item. For example, you

can access an array element in a particular structure and substructure occurrence by

appending indexes as follows:

my_struct[1].my_substruct[0].my_array[4]

Each index represents an offset from the zeroth occurrence of a structure or

substructure and the zeroth element of the array, respectively, regardless of the

declared lower bounds.

The indexed item determines the size of the index offset, as listed in Table 8-6:

Table 8-6. Indexing Structures

Indexed Item Data Type Size of Index Offset

Structure or structure pointer Not applicable Total bytes in one structure occurrence

Substructure Not applicable Total bytes in one substructure

occurrence

Simple variable or array STRING Byte

Simple variable or array INT Word

Simple variable or array INT(32) or REAL Doubleword

Simple variable or array REAL(64) or FIXED Quadrupleword

Indexing Standard Indirect Structures

The index for standard indirect structures must be a signed INT arithmetic expression

in the range –32,768 through 32,767. The offset of a structure item is from the zeroth

structure occurrence (not the current structure occurrence). Here are examples of

signed INT arithmetic expressions:

index

index + 2

index – 1

9 * index