Instruction manual

MDP PRODUCT INFORMATION
Issue 3 - Vol 2
USER GROUP NEWS
NESTED IFS
Since the statement rollowing an ir or and else can be any Rational statement, this leads immediately to the
possibility or another
ir or else As a userul example, consider this problem: The variable" r is to be set to -1 ir
"x" is less than zero; to + 1 ir "x" is greater than 100, and to 0 otherwise. Then in Rational, we write:
ir
(x < 0)
r=-1
else if (x > 100)
r=+1
else
r=o
In general, the structure
ir ( ... )
else if (
... )
else if (
... )
else
provides a way to specify the choice
of exactly one of several alternatives.
THE SWITCH STATKMENT
The switch statement provides a clean way to express multi-way branches which branch on the value of some
integer-valued expression.
The syntax is:
switch (expression) {
case
exprl:
statements
case expr2, expr3:
statements
deCault
statements
Each case is Collowed by a list oC comma-separated integer expressions. The expression inside switch is compared
against
the case expression exprl, expr2, and so on until one matches, at which time the statements following the
case are executed.
If no cases match the expression, and there is a derault section, the statements with it are
done; if there
is no derault nothing is done. (Those familiar with C should beware since the behavior is not the
same as
the C switch).
THE WHILE STATEMENT
RATFOR provides a while statement; which is simply a loop: while some condition is true, repeat this
group or statements. For example:
i = 1
while
(i < = 100) {
i=i+l
}
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