Maybe I''m crazy or just overlooking the obvious cause it''s three in the morning and I haven''t had anything that even remotely resembles sleep for the last 37 hours but this is driven me nuts. I wrote a function called DieRoll() that returns a random number between 1 and 6, and then I wrote another function that uses the output of that function and calculates a position between 0 and 20, also if the number goes over 20 it is to return to 0 and keep counting. The code for that function is as follows: if ((count+=roll) > 20) { int difference = (count+=roll) - 20; count = difference - 1; } else { count+=roll; } return count; I ran it in the debugger (I''m using VisualC++ 6.0 by the way) and this function returns the value that it''s supposed to but all of a sudden when I try to output the variable to a dialog control it comes back with a screwy new value altogether (if DieRoll() returned a 6 and count started off at 0 then all of a sudden, count magically equals 12). m_iPosition = count; UpdateData(FALSE); When I ran it through the debugger it was at UpdateData(FALSE) that it suddenly changed from 6 to 12, what the bloody frig am I missing? Can somebody please help me? It would be greatly appreciated, although I''m sure it''s something ridiculously simple that I have been overlooking.

Well...

You''re aware that every time you use += it changes the first variable? For instance, allow me to demonstrate showing in comments the actual values of count and roll at each step:

DieRoll makes roll = 6.
count = 0 (to start)

if ((count += roll) > 20))
// count = 6
// roll = 6
{
int difference = (count += roll) - 20;
// count = 6 + 6 = 12
// roll = 6
// difference = -8
count = difference - 1;
// count = -8 - 1 = -9;
}
which will do what you expect I guess, I''m not entirely sure what you''re trying to do there, but... take it from the if and throw it through your else...
if ((count += roll) > 20))
// false condition, but... count = 6, roll = 6
else
{
count += roll;
// count = 6+6 = 12
// roll = 6
}

So... that''s where the 12 is coming from.
You need to probably change, if I''m understanding you correctly, the
if ((count += roll) > 20)
to
if ((count + roll) > 20)
so that count isn''t incremented by the value of roll twice during the else.

-fel
I hope that makes sense. *blink*

Your getting unexpected numbers back because
if ((count+=roll) > 20)... adds 6 to the "count" variable, and since the result is less then 20... 6 is added again in the "else" statement.

If I am understanding what you want to do... Try this..

if ( ( count + roll ) > 20 )
{
int difference = ( count + roll ) - 20;
count = difference - 1;
}
else
{
count += roll;
}
return count;

Or better yet..
if ( ( count += roll ) > 20 )
{
count -= 21;
}
return count;


Edit:
Whoops didn't see felisandria's reply. I was disconnected while trying to post.



Edited by - Boke on July 5, 2001 2:51:04 AM

Thank you very much for pointing that out to me. I knew it was something ridiculous I was
overlooking. It''s hard to see something so obvious when your doing some late night coding though.