SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
In case 1 above, the indicated item is filed at the head (tail) of the set. In 2, the position of filing is
specified relative to some entity already in the set. The actions that take place when a file first
statement is executed are illustrated by two examples. The examples use a set whose owner and
member entities are both temporary, but they can as well be both permanent, or one permanent and
one temporary. The set and the entities are defined by the statements:
temporary entities
every FARM owns a KENNEL
every DOG has a LICENSE
and belongs to some KENNEL
The two illustrations are included in the program segment shown below. We first consider the situation
before and after the first dog is filed in a kennel. Later we examine a subsequent situation.
Assume a FARM has been created whose identifying value is stored in the global variable FARM.
This could have been done by the statement create a FARM.
Program segment:
read NUMBER.OF.DOGS
for I = 1 to NUMBER.OF.DOGS
do
create a DOG
read LICENSE(DOG)
file DOG first in KENNEL(FARM)
loop
The entity FARM is shown in figure 4-13a. After the first dog is created, its entity will appear as in
figure 4-13b.
A: B:
FARM
F.KENNEL
L.KENNEL
N.KENNEL
DOG
LICENSE
P.KENNEL
S.KENNEL
M.KENNEL
Figure 4-13. Entity Structures for FARM and DOG
At this point the variables F.KENNEL, L.KENNEL, N.KENNEL, P.KENNEL, S.KENNEL, and
M.KENNEL are all zero, indicating that KENNEL(FARM) is empty and DOG is not in some KENNEL.
A M.KENNEL is equal to 0.
After the file statement is executed, the entity records are as shown in figure 4-14. The owner
entity FARM points to the member entity DOG, which, being the only entity in KENNEL(FARM), is
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