SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
means add the current value of X to the current value of Y, giving Y a new value.
A variable identifying name is any combination of letters, digits, and periods that contains at least
one letter, so that it may be distinguished from a number. For example, X, COST,
ACCOUNTS.RECEIVABLE, SIZE, MAN3, PART1, 5Y, and 1A are all legal names, whereas 27,
1, and 4.6 are not. A slight restriction on variable naming is that any periods appearing as the last
characters of a name are completely ignored. Upper and lower case distinctions are also ignored.
Thus, Myvar, MyVar, and MYVAR all refer to the same quantity. It will be shown later in this
manual how this rule may be used as a notational aid.
Hereafter, whenever a variable name is used in a statement, it is understood to refer to the value of
the variable identified by that name, not to the name itself. The values given to numeric variables
may be whole numbers (integers) or numbers with a fractional part (decimal numbers). Thus, the
value associated with a variable named X may at various times be 0 or 125 or 16.72 or -0.00001,
or whatever number has most recently been assigned to X. The range in magnitude of numbers that
can be internally represented in a computer and the accuracy with which numbers can be represented
are, of course, subject to limits. These limits depend on the particular machine but, for the
present, may be taken to be sufficiently generous not to be the subject of concern.
At the start of program execution, the value of each numeric variable is set equal to zero. These
variables are said to be "initialized to zero."
1.3 Reading Input Data
One way in which specific numeric values can be assigned to program variables is by reading numbers
as input data. An example of the read statement is:
read X, Y and QUANTITY
X, Y, and QUANTITY are variable names. They are used in this statement in a variable name list.
In general, a SIMSCRIPT II.5 list consists of a string of quantities separated by either a comma, or
the word and, or a comma followed by the word and. Some examples of variable name lists as they
might appear in read statements are:
read PRICE, QUANTITY, DISCOUNT
read PLACE and DISTANCE
read NAME, DATE, PLACE and TIME
read NAME, and DATE, PLACE and TIME
The general form of a read statement is:
read variable name list
When a SIMSCRIPT program executes a read statement, it reads as many fields from the input
data as there are variable names listed in the statement. Successive numeric values are read and
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