SWITCH - can it be used with an expression

[golive]

Can one use a condition in the CASE statement?

I tried this but it doesn't work.

Code: Select all

     switch tCount
         case tCount <10
            -- do something
            break
         case tCount <20
             -- do something else
            break

[SparkOut]

Yes, just leave out the reference to tCount in the switch statement and only in the conditional tests

Code: Select all

switch
  case tCount >20
    answer "count is high"
    break
  case tCount <5
    answer "count is low"
    break
  default
    answer "count is just right"
    break
end switch

[SparkOut]

Also, a switch statement unmatched with a variable like that can check multiple conditions such as

Code: Select all

switch
  case tGender is "male"
    set the cPermission of this stack to false
    answer "Sorry, ladies only"
    break
  case tAge < 18
    set the cPermission of this stack to false
    answer "Sorry, adults only"
    break
end switch

[bn]

Hi golive,

you might also have a look here:

http://forums.livecode.com/viewtopic.php?f=8&t=25082

switch statements can get very tricky.

I mostly use if-then, except when choosing from a larger number of options. Then I use the "switch variable" form. With appropriate break.

If you do conditionals on a variable as done in above link, be careful and know what you are doing. You can get surprising result. Although they are consistent with the logic of Switch case.

Kind regards
Bernd

[FourthWorld]

Switch statements are trickiest when you use the case evaluation form without break statements. Beyond that very specific circumstance outlined in the forum discussion Bernd linked to, they're pretty straightforward and very useful for a wide range of circumstances where if-then blocks may be cumbersome or less flexible.

The key here is that you can either evaluate a condition in the switch statement, or within each case statement, but not both.

As SparkOut wrote, in your code you were evaluating the condition with each case statement, so just removing the comparison value from the switch statement addresses the issue you encountered.

[golive]

Very useful info from all, many thanks.

Suggestion: For beginners like me, more info like the above in the Dictionary would be useful