SIMSCRIPT II.5 Programming Language

Programming Language Concepts
for I = 1 to N, read A(I)
Here, a free-form read reads a sequence of values across the current input record. If the values are
packed, however, with no blanks between them, the individual data fields cannot be identified by
the free-form read. An alternative might be to write:
for I = 1 to N, read A(I) as I 4
This form may be used if the values of A(I) are spaced across entire records. If, however, the data
are arranged so that values are contained only in columns 1 through 60 of successive 80-byte data
records, the above statement will read through column 60 and attempt to take values from columns
61 through 80. The read must be directed to skip to a new input record upon reaching column 61.
An expression enclosed in parentheses, placed before a format list, repeats that format list the indicated
number of times and then skips to a new record. The statement above should be written as:
for I = 1 to N, read A(I) as (15)I 4
If N = 12 and four numbers are to be read per record from columns 1 through 24, the following
statements read 12 values from 3 records:
start new record
for I = 1 to N, read A(I) as (4)I 6
This form may also be used if groups of variables with different formats are in a record. The following
statement reads four pairs of data fields in the format I 6,D(6,2) from each data record
until 2*N values have been read:
for I = 1 to N, read A(I), B(I) as (4) I 6, D(6,2)
Such a repetition facility can be used with both read and write statements, but it can only be
used in statements controlled by for phrases. This particular form of the read statement assumes
that input starts at the beginning of a data (record), which explains the start new record statement
in the foregoing example. The statement can terminate, of course, with the current input pointer
positioned in the middle of a record, depending on the format used.
Similar rules apply to the print and list statements, as well as to all input/output operations performed
by the SIMSCRIPT II.5 system. Output is printed wherever the current pointer points, assuming
it is at the head of a record. After output, the system positions the pointer at the head of the
next record.
3.4.5 Variable Formats
The use of format descriptors containing expressions as well as constants is one feature available in
read and write statements that has not been discussed. Arithmetic expressions can be used to
control field widths in formats for data-layout purposes. For instance, a curve of the natural log
function, using * as a graphical character, is generated by the statement:
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