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Two looping constructs are provided: while and
do...while.
The syntax of a while loop is:
while cond stmt |
Newline after cond is obligatory.
do stmt while cond |
As usual do...while loop differs from its while
counterpart in that its stmt is executed at least once.
The looping constructs can be nested to any depth.
Two special statements are provided for branching within loop
constructs. These are break and continue.
Break statement stops the execution of the current
loop statement and passes control to the statement immediately
following it
while $x < 10
begin
if $x < $y
break
...
x = $x + 1
end
print "OK\n"
|
In the example above, execution of break statement passes
control to print statement.
Break may also take an argument: a literal number representing
the number of nested loop statements to break from. For example, the
break statement in the sample code below will exit from the
outermost while:
while $y < 10
begin
while $x < 10
begin
if $x < $y
break 2
...
x = $x + 1
end
...
y = $y + 1
end
print "OK\n"
|
Continue statement passes control to the condition of the
current looping construct. When used with a numeric argument, the
latter specifies the number of the nesting looping construct to
pass control to (as with break, the innermost loop is
considered to have number 1, so continue is equivalent
to continue 1).
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