SIMSCRIPT II.5 Programming Language

Programming Language Concepts
complete program may have only one main routine. The main routine, like all other program sections,
should be terminated by the word end.
A subprogram definition statement precedes the statements belonging to each subprogram and:
1. Declares that the statements following are part of a subprogram
2. Names to the subprogram
3. Sets up a communication mechanism for passing data to and from the subprogram.
Each subprogram has a name, which is declared in the subprogram definition statement that precedes
the statements composing the body of the subprogram. Subprogram names follow the same
naming conventions as variables (see paragraph 2.1). Each variable and subprogram name must be
unique. A subprogram definition of the simplest form is:
routine name
The optional words to and for are allowed after the word routine. Thus, a program to calculate
square roots might be named SQUARE.ROOT and could be defined by the statements:
routine SQUARE.ROOT
or
routine for SQUARE.ROOT
or it might be named TAKE.SQUARE.ROOT and be defined by the statement:
routine to TAKE.SQUARE.ROOT
As the words to and for are optional, there are obvious ambiguities in using the words to and for
as subprogram names.
Execution of the statements within a subprogram may be requested from another routine by referencing
the subprogram name. Such reference is known as calling the subprogram and commonly
takes the form:
call name
This is the simplest form of the call statement. Additions to this statement and alternative routine
references will be discussed in following paragraphs.
Each subprogram is defined with a routine statement. As for other program sections, an end
statement indicates the physical end of the routine. The statements in between constitute the body
of the subprogram. The logical end of a routine, rather than the physical end, is normally indicated
by the special statement:
return
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