Sometimes you may want to repeat a sequence of statements. Ultra Fractal provides two constructs to do this: the while loop and the repeat loop. Here is the syntax:

  while <boolean-expression>    <statements>  endwhile    
  repeat    <statements>  until <boolean-expression>    

The while loop repeats the statements as long as the boolean expression is true. If the boolean expression is or becomes false, the statements are never or no longer executed. The repeat loop, however, repeats the statements until the boolean expression becomes true. This means that the statements are always executed at least once.

If you want the statements to be executed at least once, use the repeat loop. Otherwise, use the while loop.

Here is an example that calculates x = n! (defined as x = 1*2*3*…*(n-2)*(n-1)*n), first using a while loop, and then using a repeat loop:

  int n = 23   ; or another value  float x = 1  ; float because 23! is very large  while (n > 1)    x = x * n    n = n - 1  endwhile    
  int n = 23  float x = 1  if n > 1    repeat      x = x * n      n = n - 1    until n == 1  endif    

Obviously, the while loop is better suited to calculate the factorial of a number, but in other cases the repeat loop may be better.

As with if statements, loops may be nested as much as you want.

Next: Functions

See Also