SIMSCRIPT II.5 Programming Language

Programming Language Concepts
during program execution, before the data are read using a free-form read statement. These functions
and logical values, sometimes called "look-ahead functions," are shown in table 2-4.
Table 2-4. Look-Ahead Functions
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Name
data
sfield.f
efield.f
mode
Value
End of data indicator: ended or not ended
Starting column number of the next data field
Ending column number of the next data field
Mode of the next data field: integer, real, or alpha
card
First data field on card indicator: new or not new
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Some examples illustrate the use of these system variables:
1. Frequently, the logical condition for terminating processing is reaching the end of the input
data. This condition may be tested for with logical comparisons of the form:
if data is ended
until data is ended
while data is not ended
2. Sfield.f can be used to distinguish input data records that appear in two formats. Some
of the records contain data beginning in column 1, while in others the data fields start in
column 25. These two record types are to be processed differently. A value for sfield.f
is determined before each new value is read, but the data item itself is not read until a read
statement is executed.
if sfield.f eq 1
read DATA1
else
if sfield.f eq 25
read DATA25
else
skip 1 record
always
always
3. Efield.f may be used in the same way to determine the last column position of the next
data field. Using both functions, the number of characters in a data field may be determined
before the field is read and processed.
4. The mode property of a data field may be tested to discriminate between integer and
real numeric data, or any non-numeric data, identified as alpha. A succession of name
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