SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Basic Concepts
assigned to corresponding variables in the read list. The numbers can be entered in the input data
in integer or decimal form. For example, the numbers 5, 5.0, and 5.000 are equivalent.
Data items read into or printed by a computer are treated in physical groupings called records. Examples
of a record are a single line typed on a computer terminal, a record, or a line printed on a
printer. Within a record, data items are considered to be separated into fields. A field is a contiguous
string of symbols delimited at the beginning and the end by at least one blank. Numeric data
fields may also be delimited by the beginning or the end of a record. Each numeric value occupies
one data field.
Successive read statements do not necessarily read new input records, because a SIMSCRIPT II.5
program can treat input data as a continuous stream of data fields. The precise location, then, of a
number within a record is not considered. An example illustrates this "free-form" concept: Read
X, Y, Z sets X to the value 3, Y to the value 2.1, and Z to the value 67.33 when each of the sets
of input data records in table 1-1 is read.
Table 1-1. Sample Data Records
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Record Number Values
(1) record 1 3.0 2.1 67.33
(2) record 1 3.00
record 2 2.1 67.33
(3) record 1 3
record 2 2.1
record 3 67.33
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1.4 Constants
Program statements may use numbers directly, such as the "2" in add 2 to SUM, or the number
"3.14" in add 3.14 to VOLUME. These numbers are called constants. When used, they refer to
their literal values. They are not names of variables and do not represent other values.
Constants may have the same range of numeric values as variables, and where appropriate, may be
used interchangeably in all computations. Constants differ from variables in that their values cannot
be changed. Add 5 to X is a legal use of the variable X and the constant 5. Add 5 to 4 is not
a legal use of the constant 4 because it is giving a new value of 9 to the constant 4.
Whole numbers and fractional numbers, signed or unsigned, are allowed as constants. When equivalent
representations of a number exist, they have the same value; 2.5 and 002.500 both represent
the same number. The statements add 1 to COUNTER and add 1.00 to COUNTER have the
same effect.
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