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4.5) while...do...endwhile Statement


If you need a loop for which you don't know in advance how many iterations there will be, you can use the WHILE statement. This takes the form:

WHILE condition DO statement

Or

WHILE condition DO BEGIN
   statement 1
   statement 2
   statement2
ENDWHILE

Here, the "condition" is constructed in the same way as the IF statement, and whilst the conditions is true, the statements within the loop will continue to be executed. So for example:

I = 0
WHILE I lt 10 DO BEGIN
   print, I
   I++
ENDWHILE

This will print the numbers 0 to 9 to the screen.