SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
is somewhat more descriptive. Note that the word input is optional. If input is not specified,
this usage of the skip statement is distinguished by context from that used to skip output print lines.
The word records implies input, while lines implies output.
The skip record statement can be generalized to the form:
skip E records
in which case the current data record and the following E - 1 records are bypassed. If the expression
(E) is zero, no records are skipped. If it is negative, the program terminates with an error message.
The statement:
skip 3 records
skips the remainder of the current data record and also the next two data records. (See paragraph
3.5.2 for program termination on end-of-file.)
1.10 Logical Expressions
Normally, computation proceeds from statement to statement in the order in which statements physically
appear in a program listing. For example, in the four-statement example in paragraph 1, the
program first executes the read statement, then the add statement, then the print statement, and
halts when it reaches the stop statement. A fundamentally important extension of the concepts developed
so far is the ability to specify, in a program, conditions under which alternative actions
should be performed.
Arithmetic expressions may be combined, using relational operators, to form logical expressions,
which may be determined to be either true or false and then may be used to choose between alternative
actions. A logical expression is formed by joining two arithmetic expressions with a binary
relational operator. The relational operators are:
= equal
≠ not equal
< less than
≤ less than or equal
> greater than
≥ greater than or equal
When a logical expression is encountered during the execution of a program, the current values of
the variables or arithmetic expressions that make up the logical expression are used to determine its
truth or falsity. Thus, if X = 1 and Y = 0, the logical expression:
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