SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
8. A subscripted local variable that does not appear in a define statement within a routine
has its dimensionality defined by its first use. That is, even if a routine's normally condition
is zero-dimensional, the statement let X(1) = 0 implicitly defines X as one-dimensional.
However, the array must still be reserved before its first use.
9. Definition statements for local variables placed at the head of a routine are not preceded by
preamble and followed by end, as are similar statements in a program preamble. In fact,
normally and define statements can be used anywhere within a routine, although it is
good practice to place them before any instruction statements.
2.12 Routine Arguments
Global variables provide one mechanism by which values may be communicated between program
routines. A preferred way is through routine arguments. Arguments are values that are explicitly
transmitted between calling and called routines. By making the transmission of values between routines
explicit, rather than using global variables, the logical interaction between these routines may
be emphasized, reducing the risk of inadvertent interaction. Arguments represent variables that behave
as local variables of a called routine, but which may either receive initial values each time the
routine is called, termed given arguments, or may be used as yielded arguments to transmit result
values back to the calling routine. In the case of given arguments, the initial values are supplied
by the calling routine. Numeric yielded arguments are initialized to zero, as for normal local
variables.
When a routine definition is written, those local variables that are to be arguments of the routine
are listed in the routine definition statement. This definition list is termed the formal argument list.
When a routine with arguments is called, the values that are to be used to initialize or receive values
from the argument variables are listed in order corresponding to the formal argument list in the routine
definition. The called routine may return values to a calling routine by assigning the values to
those of its argument variables defined to be yielded arguments. Those yielded arguments not
assigned a value in the routine retain the initialized values of zero. The general form of a routine
definition is:
routine name given given argument list yielding yield argument list
Consider, for example, the common square-root calculation discussed above. A routine to evaluate
the square root of a number might be written:
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