SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
When a let statement is executed, the current values of the variables on the right of the equal symbol
(=) are used to compute the value of the arithmetic expression. This value is then assigned to
the variable on the left of the equal symbol.
Used in this way, in conjunction with the word let, the equal symbol is an assignment operator.
In the statement:
let X = Y * 2
the value of the expression Y * 2 is computed and assigned to the variable X. The previous value
of X is replaced by the new value; and in:
let X = X + 1
a new value of X is computed by adding 1 to the current value of X and assigning this new value to
X. Use of the word let is optional. That is, the = operator is enough for assigning an expression to
a variable.
1.7 Specialized Computation Statements
Because addition and subtraction are such frequently used operations, two special statements,
combining both expression evaluation and assignment operations, may be used. The add and
subtract statements are used to add or subtract the value of an arithmetic expression to or from a
program variable. The statement forms are:
add arithmetic expression to variable
subtract arithmetic expression from variable
The statements are equivalent to the let statements:
let variable = variable + arithmetic expression
let variable = variable - arithmetic expression
The add and subtract statements have the virtues of being easy to write and being straightforward
in meaning. Some examples of these statements are:
add 1 to COUNTER
add ITEM * COST to BILL
subtract 3 * X + 6 * Y from Z
subtract COST from CASH
1.8 Displaying the Results of Computation
The print statement was used in the first example in paragraph 1 to display the result of a computation.
This statement may be used either to display some predefined text, or to display both predefined
text together with the current values of program variables or arithmetic expressions, as in:
print I lines as follows
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