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Re: Bug in SWITCH - ELSE: statement? [message #56232 is a reply to message #56231]

Fri, 12 October 2007 12:43

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Thu, 11 Oct 2007 09:44:27 +0000, Spon wrote:

> Hi everyone,
>
> can someone explain this to me please?
>
>> [quoted text muted]
> The ELSE clause of the SWITCH statement is optional. If included, it
> matches any selector expression, causing its code to be executed. For
> this reason, it is usually written as the last clause in the switch
> statement. **The ELSE statement is executed only if none of the
> preceding statement expressions match.** If an ELSE clause is not
> included and none of the values match the selector, program execution
> continues immediately below the SWITCH without executing any of the
> SWITCH statements.
>
> But, for example:
>
> PRO SWITCHTEST
>
> N = FIX (6 * RANDOMU (S, 1) ) + 1
>
> SWITCH N OF
> 1: PRINT, 'One'
> 2: PRINT, 'Two or less'
> 3: PRINT, 'Three or less'
> 4: PRINT, 'Four or less'
> 5: PRINT, 'Five or less'
> 6: PRINT, 'Six or less'
> ELSE: PRINT, 'Are you using loaded dice?'
> ENDSWITCH
>
> PRINT, N
> END

You probably wanted CASE, which has an implicit BREAK after each
statement. Or put the BREAKs in yourself:

1: begin
print, 'One'
break
end

SWITCH is really useful only when you want to "fall through" to multiple
processing steps. If you do want to fall through, you must BREAK
somewhere before ELSE:

SWITCH N OF
1: PRINT, 'One'
2: PRINT, 'Two or less'
3: PRINT, 'Three or less'
4: PRINT, 'Four or less'
5: PRINT, 'Five or less'
6: begin
PRINT, 'Six or less'
break
end
ELSE: PRINT, 'Are you using loaded dice?'
ENDSWITCH

Yes, it's ugly.

JD

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[Message index]

		Re: Bug in SWITCH - ELSE: statement? By: R.G.Stockwell on Fri, 12 October 2007 13:56
		Re: Bug in SWITCH - ELSE: statement? By: Matt[2] on Fri, 12 October 2007 13:40
		Re: Bug in SWITCH - ELSE: statement? By: JD Smith on Fri, 12 October 2007 12:43
		Re: Bug in SWITCH - ELSE: statement? By: R.G.Stockwell on Thu, 11 October 2007 09:47
		Re: Bug in SWITCH - ELSE: statement? By: Paul Van Delst[1] on Thu, 11 October 2007 09:42
		Re: Bug in SWITCH - ELSE: statement? By: Paul Van Delst[1] on Thu, 11 October 2007 09:27
		Re: Bug in SWITCH - ELSE: statement? By: larkn10 on Thu, 11 October 2007 08:39

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