Xbasic for Everybody : nextMeeting function crashing application

[Steve T]

I'm currently following the Xbasic For Everybody book (Version 8) but using Version 10. So far all the examples have worked but I've come across a function at page 84, nextMeeting() which crashes my Alpha Five session (not responding). It appears to be associated to the default nature of the argument. When I purposely enter a date value the function correctly returns a result. If I enter, at the interactive window, ? nextMeeting(), Alpha Five crashes. I'm running Windows Vista.

Here is the offending function.

FUNCTION nextMeeting AS D (input=date())

dim m as n
dim day as n
dim y as n

m=month(input)
y=year(input)

try:

if m=8 then
	' no meeting in August, advance month to September
	m=m+1 
end if
' get second wednesday of month

trial_date=nth_dow("friday",m,y,2)

if trial_date<input then
	' we already passed the meeting for the month - find next month's date
	m=m+1
	goto try 
end if
 
nextMeeting=trial_date
END FUNCTION

I've checked the help file, which relates to Version 9, and have re-written the header of the function like so,

FUNCTION nextMeeting AS D (input=date() as D )

but that had the same effect, that is, Alpha Five crashes.

Any clues please?

[Tom Cone Jr]

Re: Xbasic for Everybody : nextMeeting function crashing application

The original function does not take into account the need to
re-set the month and year variables after December each year.

Here's the mod that makes things right:

[FONT="Courier New"][SIZE="2"]'Date Created: 22-Dec-2009 09:02:28 PM
'Last Updated: 22-Dec-2009 09:06:48 PM
'Created By  : Tom Cone Jr
'Updated By  : Tom Cone Jr

FUNCTION nextMeeting AS D (input=date())

dim m as n
dim day as n
dim y as n

m=month(input)
y=year(input)

try:

if m=8 then
	' no meeting in August, advance month to September
	m=m+1 
end if
' get second wednesday of month

trial_date=nth_dow("friday",m,y,2)

if trial_date<input then
	' we already passed the meeting for the month - find next month's date
	m=m+1
	[COLOR="Red"]if m > 12 then    'm should never be greater than 12
	    m = m - 12    'when it hits 13, subtract 12, then
	    y = y + 1      'increment the year
	end if[/COLOR]	
             goto try 
end if
 
nextMeeting=trial_date
END FUNCTION[/SIZE][/SIZE][/FONT]

[Steve T]

Re: Xbasic for Everybody : nextMeeting function crashing application

Thanks Tom, that did the trick.

On reflection I should have studied the code more closely but assumption kicked in, believing that it must be correct as it's in the book.

[Tom Cone Jr]

Re: Xbasic for Everybody : nextMeeting function crashing application

You're welcome. I suppose no one noticed it before because it only locks up if the date passed to the function is in the last half of the last month each year. Just your luck to come along when you did ! -- tom

[Peter.Wayne]

Re: Xbasic for Everybody : nextMeeting function crashing application

Thanks, Tom.
Only problem now is that the code is commented to find a "Wednesday" but the actual code searches for "friday".

Got you there, Tom!

- Peter

[Tom Cone Jr]

Re: Xbasic for Everybody : nextMeeting function crashing application

Well, gosh darn it! So you have! -- tom