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WHILE/DO loops
A language must have some form of flow control to be something better than a batch processor. The simplest form of flow control, beyond IF-ELSE is the DO loop. The first construct is the WHILE / DO loop:
while ( EXPRESSION ) {
STATEMENTS;
}
Note that the DO is implied. If the condition is initially false,
the body of the loop will never execute.
In the next form, the loop will execute at least once.
do {
STATEMENTS;
} while (EXPRESSION);
All loops support the following two control statements:
- last
- Declare that this is the last statement in the loop; completely exit the loop even if the condition is still true, ignoring all statements up to the loop's closing brace.
- next
- Start a new iteration of the loop
# one way to count to 10
$number = 0;
while(1) {
$number++;
if ($number >= 10 ) {
last;
}
}
The National Center for Supercomputing Applications
University of Illinois at Urbana-Champaign
johnsonb@ncsa.uiuc.edu
Last modified: June 19, 1997