While Loop

[Steven P]

Good morning,

 

 

Is there something similar to a while loop that will exit the loop part way through if the condition is reached?

 

 

For example

 (setq test 0)
 (while (<= test 10)
   (setq test (1+ test))
   (princ test)
   (setq test (1+ test))
   (princ test)
   (setq test (1+ test))
   (princ test)
 )

 

 

Will return a count in the command line, 1 to 12, then the next time round 'while' sees 'test' is greater than 10 and doesn't do the loop again.

 

 

What I am wanting is the loop to count 1 to 10, then exit the while loop.

 

 

So is there anything simple that will do this?

 

 

Thanks

[Tharwat]

Hi,

 

As long as you have specific number of loops then you can use REPEAT function but while function also should work.

 

(repeat 10
           (......)
         )

[Grrr]

(while <test statement> [color="green"]; if true, do the expressions below, if false - don't evaluate the expressions/stop the loop[/color]
 <expressions> [color="green"]; evaluate the expressions, and run the <test statement> again[/color]
)

 

Whats happening is that you are incrementing the value 3 times per check, I think that you have to increase the value once at every check:

 

(setq n 0)
(while (< n 10)
 (setq n (1+ n))
 (print n)
)

 

Or check the every sub-increment, which is frustrating:

 

(setq n 0)
(while (<= n 10)
 (while (<= (setq n (1+ n)) 10)
   (print n)
   (while (<= (setq n (1+ n)) 10)
     (print n)
     (while (<= (setq n (1+ n)) 10)
       (print n)
     )
   )
 )
)

 

But if you really just want to increment like that, use repeat function like Tharwat mentioned (its the fastest).

[Steven P]

Thanks, perhaps I should have explained it better. Replace (setq test (1+ test)) with calls to other subroutines, each of these might take Test to above 10 sometime, but I don't want the subsequent sub routines to run when it does (for example 1st loop, routine_1 and test = 3, routine_2, test = 5, routine_3 test = 8, 2nd loop, routine 1 and test = 9 routine_2 test = 12 so stop loop before routine_3 is called)

 

 

 

 

Tharwat - repeat works well for how I first described my problem, thanks

Grrr - I want to do the frustrating method but in a less frustrating manner

[Lee Mac]

Maybe something like this?

(setq test 0)
(while
   (and
       (< test 11)
       (progn
           (setq test (1+ test))
           (< test 11)
       )
       (progn
           (setq test (1+ test))
           (< test 11)
       )
       (progn
           (setq test (1+ test))
           (< test 11)
       )
   )
)

[Steven P]

Thanks Lee, as always a great solution, I never knew you could add 'and' to a while command like that

[Lee Mac]

Thanks Lee, as always a great solution, I never knew you could add 'and' to a while command like that

 

You're welcome Steven - any expression can constitute the test expression for a while loop.