The while looping instruction is used to repeat a block of instructions until a certain condition is true.

 

Before the block to be repeated, place a while statement containing the boolean expression that determines if the loop will be performed.

while SomeBooleanExpressionIsTrue
   // do something
endwhile

The whole point of the while loop is to re-evaluate a condition prior to every loop (which means that if the condition is false from the beginning, the loop will never be entered). Recall that the elements of a for loop could not be modified in the loop, nor could they vary, but in the case of a while loop the following is allowed and often used.

// increase the date until we reach a Saturday
while WeekDayOf(nDate) <> 6
   inc(nDate)
endwhile   

To interrupt the flow of a while loop, use the break or continue commands.

 

See also: for loops.

 

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Topic 105132, last updated on 18-Apr-2020