While
Statement
Runs a sequence of statements while a given condition is true.
Syntax
While condition
[ statements ]
End [ While ]
Parts
condition
- Mandatory Boolean expression.
statements
- Optional one or more statements.
They run while
condition
is true. - The alternative is two or more blocks of statements.
The initial group starts with
Exit When
, and runs the same as given above. The subsequent groups start withWhen
, and run when (1) the loop cannot start, or (2) after the loop stops. See § When statements for more information. End
- Completes the statement.
You can also use
End While
. - You can change this part of the syntax. See @Option Directive § End for more information.
Instructions
Use the construct While
when you must run one or more statements again and again.
It is recommended when you cannot be sure how many times the statements must run.
Control is connected with the Boolean condition
after While
.
Other loop constructs are possibly more flexible or can give better performance.
See the See also section below for more information.
Usual operation
If condition
is true, statements
run.
After End
, control moves back to While
, where condition
calculates again.
While condition
stays true, statements
continue to run.
But when it becomes false, control moves to the statement after End
.
condition
always calculates before statements
run.
But if condition
is initially false, statements
do not run.
Exit While
The statement Exit While
can stop While
.
Exit While
immediately moves control to the statement after End
.
When
statements
To find if While
completed because condition
became false, use When DONE
.
To find if While
was not run because condition
was initially false, use When NONE
.
See Exit When
Clause for more information.
Examples
Dim counter = 5
Dim factorial = 1
While counter > 0
factorial *= counter
Counter -= 1
End While
See also
- Do…Loop Statement – Is more flexible in the location of the condition.
- For Statement – Gives better performance when run a given number of times.
- For Each Statement – Runs through a given data structure.
- Exit Statement
- Exit When Clause
- Loop Constructs