User Tools

Site Tools


while

Synopsis:

while (<condition>) <action>
while (<condition>) [{ <action> }]

Description:

The WHILE loop is a sort of hybrid between the FOR loop and the IF control statement. It allows for repetitive action, as with FOR, but the loop iterates (performs the action) only if a specific condition is met, as with IF.

The “condition” portion may contain any comparison or assignment allowed in an IF statement.

Examples:

To display a warning message 3 times:

    @ xx = 3
    while ( xx > 0 ) {
       echo WARNING!  This ship will self destruct in $xx seconds!
       @ xx--
    }

A infinite loop that behaves like the Unix 'yes' command:

    while ( 1 ) echo yes

Aliases:

UNTIL is the exact opposite of WHILE. It is essentially the same applying the negation operator (!) to the entire WHILE condition.

Other Notes:

WHILE has all of the capabilities of FOR, only in a different syntax. The distinction between the two is not great enough to warrant a recommendation of one over the other. If anything, FOR tends to be more concise than WHILE; however, this is not always the case.

while.txt · Last modified: 2006/08/29 16:08 (external edit)